Answer :
It's a right triangle, so there is a 90 degree angle.
SOH CAH TOA
SIN=side opposite/hypotenuse
COS= side adjacent/hypotenuse
use 180-90 to represent the remaining degree value if beta and theta are summed.
SOH CAH TOA
SIN=side opposite/hypotenuse
COS= side adjacent/hypotenuse
use 180-90 to represent the remaining degree value if beta and theta are summed.