If he heads for a point x miles from O, then the time needed is
t = √(x^2+9)/3 + (5-x)/8
dt/dx = 0 when x = 9/√55
Brian is in a lighthouse 3 miles from the nearest point O of a straight shoreline. Brian would like to visit his friend Torre who lives 5 miles up the beach from the point O. Brian can row 3 miles per hour and run 8 miles per hour. In order to get to Torres house in the least amount of time, to what point on the beach should Brian row and leave his boat?
1 answer
1 answer