Angles x and y are located in the first quadrant such that sinx=4/5, and cosy = 7/25.
a) Determine an exact value of cosx.
b) Determine an exact value of siny.
c) Determine an exact value for sin(x+y)
I'm really at a loss here, do I just sub those in to some formula or something? Can anyone help me out? Or get me pointed in the right direction? thanks in advance!!
Hello Random-HeroThe formulae you need here are:
and
So in (a), use , and remember when you take the square root to find , that, since the angle is in the first quadrant , so you don't have to worry about the negative square root.
(b) Use . And, again, since is in the first quadrant, .
(c) simply use the formula for and your answers to (a) and (b).
Can you complete it now?
Grandad