A person stands 40 meters from the base of a building. The angle of elevation from the person to the top of the building is 35°. Find the height of the building to the nearest tenth of a meter. Assume the person's eye level is at ground level.

The building, the ground, and the line of sight form a right triangle.

Relative to the 35° angle:
- The building height is the opposite side.
- The 40-meter distance is the adjacent side.

Because we know the adjacent side and want the opposite side, use tangent:
tan(θ) = opposite / adjacent

Let h represent the height of the building.

Substitute the known values:
tan(35°) = h / 40

Multiply both sides by 40:
h = 40tan(35°)

Using a calculator in degree mode:
tan(35°) ≈ 0.7002

Therefore:
h ≈ 40(0.7002)
h ≈ 28.008

Round to the nearest tenth:
h ≈ 28.0 meters

Therefore, the building is approximately 28.0 meters tall.