You are Here: Home >< Maths

# Maths A Level question help watch

1. Please can someone explain this to me, I understand everything until the bit where it says "Cancel sinθ as θ≠0° or 180°". Why do you cancel sin??

THANKS!

2. (Original post by jarjarbinkss)
Please can someone explain this to me, I understand everything until the bit where it says "Cancel sinθ as θ≠0° or 180°". Why do you cancel sin??

THANKS!
Because then you're left with a single variable of cos to solve for?

You're allowed to cancel because sin is not 0, so dividing by it is allowed.
3. (Original post by RDKGames)
Because then you're left with a single variable of cos to solve for?

You're allowed to cancel because sin is not 0, so dividing by it is allowed.
oh wait so they have just divided the whole thing by sin. Why can you not divide by sin if it equals 0 then? is it because sin 0 = 0 and dividing by 0 isn't allowed anyway?
4. We cancel the sin(ø) as it’s the next logical step. Instead of having ø appear three times in the equation we can eliminate two of them, making it much easier to solve.
Divide both sides by ‘sin(ø)’
This leaves you with [2cos(ø)]/5 = 1/4
Then multiply both sides by 5 giving you 2cos(ø) = 5/4
This can then be solved with ease.
5. (Original post by jarjarbinkss)
oh wait so they have just divided the whole thing by sin. Why can you not divide by sin if it equals 0 then? is it because sin 0 = 0 and dividing by 0 isn't allowed anyway?
Dividing by 0 is obviously not allowed, yes, and for any multiple of 180 as the argument.
6. (Original post by RDKGames)
Dividing by 0 is obviously not allowed, yes, and for any multiple of 180 as the argument.
yeah yeah i remember that now thanks
7. (Original post by -Mathematician-)
We cancel the sin(ø) as it’s the next logical step. Instead of having ø appear three times in the equation we can eliminate two of them, making it much easier to solve.
Divide both sides by ‘sin(ø)’
This leaves you with [2cos(ø)]/5 = 1/4
Then multiply both sides by 5 giving you 2cos(ø) = 5/4
This can then be solved with ease.
thank you very much

### 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: October 14, 2017
The home of Results and Clearing

### 4,531

people online now

### 1,567,000

students helped last year
Today on TSR

### IT'S TODAY!

A-level results chat here

### University open days

1. Bournemouth University
Fri, 17 Aug '18
2. University of Bolton
Fri, 17 Aug '18
3. Bishop Grosseteste University
Fri, 17 Aug '18
Poll
Useful resources

### 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

## 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