What is the measure (in degrees) of B

BC is the hypotenuse of right triangle ABC.
If AC=3, and BC=6, then what is the measure, in degrees, of B?

We know that,
sin(x) = Perpendicular/Hypotenuse
sin(B) = AC/BC = 3/6 = 1/2
Since measure of angle B lies in between 0 and 90 degrees,
B = 30 degrees (since sin(30) = 1/2)

cos A = 3 / 6 = 1 / 2
A = 60°

sin B = 3/6 = 1/2 or B = 30 degree