# Thread: Preparing for next year 4

1. ## Preparing for next year 4

Hi,

I've asked for a list of questions from a teacher to do over the holidays. I'm struggling to use the text book to help me.

Could someone provide HOW to do these questions, as I just want to get an idea of what I'm getting next year.

Thanks.

7. Find the exact solutions of $9^s^i^n^²^x + 9^c^o^s^²^x = 10$ for $0 <= x <= 2pi$

8. if $cos(a) = sin(a-B)sin(B)$ Prove that $tan(a-B)tan(B)= 1/2$

2. Originally Posted by jonoe
Hi,

I've asked for a list of questions from a teacher to do over the holidays. I'm struggling to use the text book to help me.

Could someone provide HOW to do these questions, as I just want to get an idea of what I'm getting next year.

Thanks.

7. Find the exact solutions of $9^s^i^n^²^x + 9^c^o^s^²^x = 10$ for $0 <= x <= 2pi$

8. if $cos(a) = sin(a-B)sin(B)$ Prove that $tan(a-B)tan(B)= 1/2$
Have you been taught any of the material that these questions are based on?

I will outline Q7:

Substitute $\sin^2(x) = 1 - \cos^2(x)$. Then your equation has the form $\displaystyle \frac{9}{t} + t = 10$ where $t = 9^{\cos^2(x)}$. Solve for t and then solve for cos(x) and hence x.