This is in preparing us for optimization in calculus, yet i dont understand how this diagram will look or how to solve it, can someone give someone pointers?

A man can row at 24 km/h, and run at 7 km/h. He needs to get from a point A, on the south bank of a stretch of still water, to point B on the north bank of the water. The direct distance from A to B is 25 km, and the water is 24 km wide. He starts rowing with an angle theta between North and the direction in which he rows. Find an expression for the time T he will take to get from A to B, in terms of theta.

What is the speed of running use for?

thanks in advance