Answer:
11.53°
Step-by-step explanation:
We have a right triangle, so we will calculate the sine of y, which is equal to the ratio of the length of the side that is opposite that angle to the length of the longest side of the triangle (the hypotenuse).
sin y = 4/20 = 1/5
To find y, we apply the inverse function of the sine.
sin y = 1/5
y = arc sin 1/5 = 11.53°
