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

# Addition Formula watch

1. Hello!
Can anyone help me with this question

(i) Express 24sinθ+7cosθ in the form Rsin(θ+α),where R>0and 0<α<90

(ii) Hence solve the equation 24sinθ +7cosθ = 12 for 0< θ < 360.

I've got that R=25 and that alpha= 16.3

how do i work out theta? in (i)

and then how can i use this to solve (ii) ?

2. (Original post by VeeOMGlob)
Hello!
Can anyone help me with this question

(i) Express 24sinθ+7cosθ in the form Rsin(θ+α),where R>0and 0<α<90

(ii) Hence solve the equation 24sinθ +7cosθ = 12 for 0< θ < 360.

I've got that R=25 and that alpha= 16.3

how do i work out theta? in (i)

and then how can i use this to solve (ii) ?

You don't work out theta in part i, the question is asking you to work out theta in part 2 in the given range for theta (0 to 360).

Now set and then solve.
3. (Original post by ThatPerson)
You don't work out theta in part i, the question is asking you to work out theta in part 2 in the given range for theta (0 to 360).

Now set and then solve.
Aha, It worked! Thank you very much for the help
theta=12.42 and 135.1

Turn on thread page Beta
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: January 21, 2014
Today on TSR

### Boyfriend slept with someone else

...we were on a break

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