The triangle in the image is a right triangle. We are given a side and an angle, and asked to find another side. Therefore, we should use a trigonometric function.
Trigonometric Functions: SOH-CAH-TOA
---sin = opposite/hypotenuse, cosine = adjacent/hypotenuse, tangent = opposite/adjacent
In this problem, looking from the angle, we are given the adjacent side and want to find the opposite side. This means we should use the tangent function.
tan(40) = x / 202
x = tan(40) * 202
x = 169.498
x (rounded) = 169 meters
Answer: the tower is 169 meters tall
Hope this helps!