# Thread: Preparing for next year

1. ## Preparing for next year

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.

1. Prove that:
a) $sin(x+(pi/4))+sin(x-(pi/4))=sqrt(2)sinx$
b) $sin(x+(pi/)4)sin(x-(pi/4))=sin^2 x - (1/2)$

2. Simplify $(1+sin2x+cos2x)/(1+sin2x-cos2x)$

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.

1. Prove that:
a) $sin(x+(pi/4))+sin(x-(pi/4))=sqrt(2)sinx$
b) $sin(x+(pi/)4)sin(x-(pi/4))=sin^2 x - (1/2)$

2. Simplify $(1+sin2x+cos2x)/(1+sin2x-cos2x)$
1. In both cases apply the compound angle formula for sin(A + B).

2. Substitute the double angle formulae and simplify.