The problem can be drawn as a right triangle (image attached) and we can use ratio of tan to determine the height of the building tan of the angle = side in front of the angle / side adjacent to the angle tan 48° = height of building / horizontal distance
plug the numbers into the equation above height of building / horizontal distance = tan 48° h/45 = tan 48° h = tan 48° × 45 h = 1.1106 × 45 h = 49.98 feet