Turn on thread page Beta
 You are Here: Home >< Maths

# C2 maths help watch

1. show that (2 - cos^2 x) / (1 + sin^2 x) is equal to 1

I have substituted cos^2 x by (1 - sin^2 x) but I don't know what to do next
2. what past paper is this from?
3. (Original post by man111111)
show that (2 - cos^2 x) / (1 + sin^2 x) is equal to 1

I have substituted cos^2 x by (1 - sin^2 x) but I don't know what to do next
Hi,

I did for LHS:

(2 - cos^2 x) / (1+ 1 - cos^2 x)

So, (2 - cos^2 x) / ( 2 - cos ^2 x)

which equals 1

If you substitute cos^2 x by (1 - sin^2 x):

[ 2 - (1 - sin^2 x)] / (1 + sin^2 x)

So, ( 1 + sin^2 x ) / (1+ sin^2 x )
4. (Original post by XavierD)
Hi,

I did for LHS:

(2 - cos^2 x) / (1+ 1 - cos^2 x)

So, (2 - cos^2 x) / ( 2 - cos ^2 x)

which equals 1

If you substitute cos^2 x by (1 - sin^2 x):

[ 2 - (1 - sin^2 x)] / (1 + sin^2 x)

So, ( 1 + sin^2 x ) / (1+ sin^2 x )
hi thanks for replying,
I don't understand why [2 - (1 - sin^2 x)] gives you 1+sin^2x

In addition, I don't understand why [1+ (1 - cos^2 x)] gives you 2 - cos^2 x
5. u need the rule

sin2x + cos2x = 1

so we got
2-cos2x / 1+ sin2x

we can substitute cos2x with 1-sin2x so we would get

2 - (1-sin2x)/1+sin2x {I think u forgot that u have to put brackets in}

so we would then get

2 - 1 + sin2x / 1 + sin2x

which equals to

1 + sin2x / 1 + sin2x

which then equals to
1

I think u forgot the fact that you had to put the 1 - sin2x inside a bracket.
6. (Original post by man111111)
hi thanks for replying,
I don't understand why [2 - (1 - sin^2 x)] gives you 1+sin^2x

In addition, I don't understand why [1+ (1 - cos^2 x)] gives you 2 - cos^2 x
I just opened the brackets,

for: 2 - ( 1 - sin^2 x)

equals: 2 - 1 + sin^2 x

so, 1 +sin^2 x

for: 1 + ( 1 - cos^2 x)

opening the brackets: 1 + 1 - cos^2 x

so, 2 - cos^2 x

Please let me know if this helps

Turn on thread page Beta

### Related university courses

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: May 19, 2017
Today on TSR

### Edexcel GCSE Maths Unofficial Markscheme

Find out how you've done here

Poll
Useful resources

## Make your revision easier

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams

Can you help? Study help unanswered threads

## Groups associated with this forum:

View associated groups

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE