Answer:
68.0°
Explanation:
The tangent function relates the sides of a right triangle to the angle:
Tan = Opposite/Adjacent
The mast is opposite the angle of elevation, and the shadow is adjacent, so you have ...
tan(angle) = (42 ft)/(17 ft)
The inverse tangent function is used to find the angle whose tangent is a particular value.
angle = arctan(42/17) ≈ 67.964°
The angle of elevation is about 68.0°.