A man with a boat is located at point on the shore of a circular lake of radius 4 miles. He wants to reach the point on the shore diametrically...

A man with a boat is located at point on the shore of a circular lake of radius 4 miles. He wants to reach the point on the shore diametrically opposed to as quickly as possible. He plans to paddle his boat at an angle (0<t<pi/2) to to some point on the shore, then walk along the shore to his . If he can paddle 2.8 miles per hour and walk at 3.3 miles per hour, what is the shortest possible time it will take him to reach ?