find sin(a + b) and cos (a + b) if sin(a) = 817; cos(b) = 45.

[spark turret]

expand both of the things

if you have sin(a) you can get cos(a)

same for b

remember any identity useful?

@mossy sage

sin^2(a) + cos^2(a) = 1

if you use that, and expand both sin(a+b) and cos(a+b) then you can solve it

also remember, that sin in the first quadrant is positive

same with cos

so sin(a) = +-square root of (1- cos^2(a))

but you take the positive solution

yes

yes

same for b