Answer:
We can use inverse sine (or arcsine) function to find the measure of the angle, since:
sin(theta) = opposite/hypotenuse
In this case, sin(theta) = 3/5, which means that if we draw a right triangle with one angle equal to theta, and the opposite side of length 3, and the hypotenuse of length 5, then the sine of that angle will be 3/5.
Using inverse sine function, we get:
theta = arcsin(3/5) = 36.9º
Therefore, the measure of the angle is b. 36.9º