Given: Distance from where the building can be viewed is 90ft from its base and angle of elevation to the top of the building is stated as 35°To calculate the height of the building, we will use the following trigonometry formula Tan 35° = Opposite Side/ Adjacent Side Tan 35° = H/90 H = 90 x Tan 35° H = 90 x 0.7002 H = 63.018 feet Hence, the height of the building is 63.018 feet.