Solving Similar Triangles with Indirect Measurement & Triangles Given. Step 1: Identify the sides and/or angles of the given triangle. Step 2: Calculate the third angle from the equation, ∠A=180∘−(∠B+∠C) ∠ A = 180 ∘ − ( ∠ B + ∠ C ) , where ∠A,∠B,∠C are the three angles of △ABC.
Solution. First, you stand next to the flagpole. Then you measure your height, your shadow's length, and the flagpole's shadow length at the same time. Using similar right triangles for the situation, you can write a proportion and solve for the flagpole's height.
Indirect measurement is a method of using proportions to find an unknown length or distance in similar figures. Two common ways to achieve indirect measurement involve (1) using a mirror on the ground and (2) using shadow lengths and find an object's height.