A man launches his boat from point on a bank of a straight river, 3 km wide, and wants to reach point , 8 km downstream on the opposite bank, as...

A man launches his boat from point on a bank of a straight river, 3 km wide, and wants to reach point , 8 km downstream on the opposite bank, as quickly as possible as shown in the figure. He could row his boat directly across the river to point C and then run to B, or he could row directly to B, or he could row to some point D between C and B and then run to B . If he can row 6 km/h and run 8 km/h, use Calculus to determine where should he land to reach B as soon as possible. (We assume that the speed of the water is negligible compared with the speed at which the man rows.)