From the top of a platform 5 m high, the angle of elevation of a tower was 30 deg. If the tower was 45 m high, how far away from the tower was the platform positioned?
O is the center of the circle and two tangents are drawn from a point P to this circle at points A and B. If ∠AOP = 50°, then what is the value (in degrees) of ∠APB?