Step 1: Identify the height of the building, which is 20 meters.
Step 2: Identify the distance from the person to the building, which is 15 meters.
Step 3: Recognize that we can form a right triangle where the height of the building is one side (20 meters) and the distance from the person to the building is the other side (15 meters).
Step 4: Use the Pythagorean theorem to find the hypotenuse of the triangle. The formula is hypotenuse = √(height² + distance²).
Step 6: Use the definition of sine in a right triangle, which is sin(θ) = opposite side / hypotenuse. Here, the opposite side is the height of the building (20 meters) and the hypotenuse is 25 meters.