Prove the identity:
1. sin(A-B)cosB+cos (A-B)sinB=sinA
2. Prove that sin(∏/4 + A) - sin(∏/4 - A)=Square root 2 sinA
THANK YOU
In both cases you should start by using the compound angle formulae:
sin(A - B) = sin A cos B - sin B cos A
cos(A - B) = cos A cos B + sin A sin B
sin(A + B) = sin A cos B + sin B cos A
I'm assuming there's something missing on the right hand side of the first one .......
For the second one it also helps to know that $\displaystyle \sin \frac{\pi}{4} = \cos \frac{\pi}{4} = \frac{1}{\sqrt{2}}$.
Where are you stuck?