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Understanding Sin, Cos, & Tan Coupled with Rectangle Area Calculation

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Wendy Mico Avomo

07/12/2025

Maths

Sin, Cos, & Tan + Area of a rectangle

191

7 Dec 2025

2 pages

Understanding Sin, Cos, & Tan Coupled with Rectangle Area Calculation

user profile picture

Wendy Mico Avomo

@wendymicoavomo_rbcu

Trigonometry and area calculations are essential skills you'll use throughout... Show more

Sin, Cos, Tan:

Are

hyp
Opp

Cos = adjacent
adj

opp.

adj

44
hye
sin e =
opposite
hypotenuse

Are
4
Ar
hypotenuse
hyp
tan = opposite

A
O

Trigonometry: Sin, Cos, and Tan

Trigonometry is all about the relationships between angles and sides in right-angled triangles. Think of it as a way to find missing information when you only know part of the puzzle.

The three main trigonometric ratios are sine (sin), cosine (cos), and tangent (tan). Here's what each one represents: sin = opposite ÷ hypotenuse, cos = adjacent ÷ hypotenuse, and tan = opposite ÷ adjacent.

Remember that the hypotenuse is always the longest side (opposite the right angle), the opposite side is across from your angle, and the adjacent side is next to your angle. A handy memory trick is "SOH CAH TOA" - it contains the first letters of each ratio.

You'll also need to memorise exact values for common angles like 30°, 45°, and 60°. These pop up frequently in exams, so knowing them off by heart will save you time and marks.

Quick Tip: Always label your triangle sides (opposite, adjacent, hypotenuse) before choosing which ratio to use - it prevents silly mistakes!

Sin, Cos, Tan:

Are

hyp
Opp

Cos = adjacent
adj

opp.

adj

44
hye
sin e =
opposite
hypotenuse

Are
4
Ar
hypotenuse
hyp
tan = opposite

A
O

Area Formulas for Common Shapes

Calculating area is a fundamental skill that appears in nearly every maths exam. Each shape has its own formula, but they're all logical once you understand the pattern.

For rectangles, it's simply area = length × width A=lwA = lw. Triangles are half of a rectangle, so area = ½ × base × height A=½bhA = ½bh. Parallelograms work like rectangles: area = base × height A=bhA = bh.

Trapeziums need a slightly different approach since they have two parallel sides of different lengths. The formula is area = ½ × (sum of parallel sides) × height, written as A = ½a+ba + b × h.

For circles, you'll use area = π × radius² A=πr2A = πr². Make sure you're using the radius (centre to edge) rather than the diameter (edge to edge through centre). This formula appears constantly in GCSE questions.

Exam Success: Always write down the formula first, then substitute your values - examiners give marks for showing the correct formula even if your final answer is wrong.



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The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.

Stefan S

iOS user

This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.

Samantha Klich

Android user

Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.

Anna

iOS user

Best app on earth! no words because it’s too good

Thomas R

iOS user

Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.

Basil

Android user

This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.

David K

iOS user

The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!

Sudenaz Ocak

Android user

In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.

Greenlight Bonnie

Android user

very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.

Rohan U

Android user

I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.

Xander S

iOS user

THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮

Elisha

iOS user

This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now

Paul T

iOS user

The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.

Stefan S

iOS user

This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.

Samantha Klich

Android user

Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.

Anna

iOS user

Best app on earth! no words because it’s too good

Thomas R

iOS user

Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.

Basil

Android user

This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.

David K

iOS user

The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!

Sudenaz Ocak

Android user

In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.

Greenlight Bonnie

Android user

very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.

Rohan U

Android user

I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.

Xander S

iOS user

THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮

Elisha

iOS user

This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now

Paul T

iOS user

 

Maths

191

7 Dec 2025

2 pages

Understanding Sin, Cos, & Tan Coupled with Rectangle Area Calculation

user profile picture

Wendy Mico Avomo

@wendymicoavomo_rbcu

Trigonometry and area calculations are essential skills you'll use throughout your maths GCSE and beyond. These formulas might look intimidating at first, but they're actually straightforward tools that help solve real-world problems.

Sin, Cos, Tan:

Are

hyp
Opp

Cos = adjacent
adj

opp.

adj

44
hye
sin e =
opposite
hypotenuse

Are
4
Ar
hypotenuse
hyp
tan = opposite

A
O

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Trigonometry: Sin, Cos, and Tan

Trigonometry is all about the relationships between angles and sides in right-angled triangles. Think of it as a way to find missing information when you only know part of the puzzle.

The three main trigonometric ratios are sine (sin), cosine (cos), and tangent (tan). Here's what each one represents: sin = opposite ÷ hypotenuse, cos = adjacent ÷ hypotenuse, and tan = opposite ÷ adjacent.

Remember that the hypotenuse is always the longest side (opposite the right angle), the opposite side is across from your angle, and the adjacent side is next to your angle. A handy memory trick is "SOH CAH TOA" - it contains the first letters of each ratio.

You'll also need to memorise exact values for common angles like 30°, 45°, and 60°. These pop up frequently in exams, so knowing them off by heart will save you time and marks.

Quick Tip: Always label your triangle sides (opposite, adjacent, hypotenuse) before choosing which ratio to use - it prevents silly mistakes!

Sin, Cos, Tan:

Are

hyp
Opp

Cos = adjacent
adj

opp.

adj

44
hye
sin e =
opposite
hypotenuse

Are
4
Ar
hypotenuse
hyp
tan = opposite

A
O

Sign up to see the contentIt's free!

Access to all documents

Improve your grades

Join milions of students

By signing up you accept Terms of Service and Privacy Policy

Area Formulas for Common Shapes

Calculating area is a fundamental skill that appears in nearly every maths exam. Each shape has its own formula, but they're all logical once you understand the pattern.

For rectangles, it's simply area = length × width A=lwA = lw. Triangles are half of a rectangle, so area = ½ × base × height A=½bhA = ½bh. Parallelograms work like rectangles: area = base × height A=bhA = bh.

Trapeziums need a slightly different approach since they have two parallel sides of different lengths. The formula is area = ½ × (sum of parallel sides) × height, written as A = ½a+ba + b × h.

For circles, you'll use area = π × radius² A=πr2A = πr². Make sure you're using the radius (centre to edge) rather than the diameter (edge to edge through centre). This formula appears constantly in GCSE questions.

Exam Success: Always write down the formula first, then substitute your values - examiners give marks for showing the correct formula even if your final answer is wrong.

We thought you’d never ask...

What is the Knowunity AI companion?

Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.

Where can I download the Knowunity app?

You can download the app from Google Play Store and Apple App Store.

Is Knowunity really free of charge?

That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.

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Most popular content: Trigonometric Ratios

Most popular content in Maths

Most popular content

Can't find what you're looking for? Explore other subjects.

Students love us — and so will you.

4.9/5

App Store

4.8/5

Google Play

The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.

Stefan S

iOS user

This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.

Samantha Klich

Android user

Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.

Anna

iOS user

Best app on earth! no words because it’s too good

Thomas R

iOS user

Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.

Basil

Android user

This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.

David K

iOS user

The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!

Sudenaz Ocak

Android user

In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.

Greenlight Bonnie

Android user

very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.

Rohan U

Android user

I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.

Xander S

iOS user

THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮

Elisha

iOS user

This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now

Paul T

iOS user

The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.

Stefan S

iOS user

This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.

Samantha Klich

Android user

Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.

Anna

iOS user

Best app on earth! no words because it’s too good

Thomas R

iOS user

Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.

Basil

Android user

This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.

David K

iOS user

The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!

Sudenaz Ocak

Android user

In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.

Greenlight Bonnie

Android user

very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.

Rohan U

Android user

I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.

Xander S

iOS user

THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮

Elisha

iOS user

This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now

Paul T

iOS user