Since this is a right triangle, we can use one of the three main trigonometric functions: sine, cosine, or tangent.
Remember: SOH-CAH-TOA
Looking from the angle, we know the opposite side and the hypotenuse. Therefore, we should use the sine function.
sin(x) = 21/40
x = sin^-1(21/40)
x = 32 degrees
Hope this helps!
