Question

Given:
sin(x) = 2/3 and cos(y) = 3/4

Find the values of:
a) sin(x+y)
b) cos(x-y)
c) tan(x+y)

Answer 1

They are the general formula you have to learn:

\[\sin(x+y) = \sin(x) \cos(y) + \cos(x) \sin(y)\]

\[\cos(x-y) = \cos(x)\cos(y) + \sin(x)\sin(y)\]

\[\tan(x+y) = \frac{\tan(x) + \tan(y)}{1 - \tan(x)\tan(y)}\]