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Home > PC > Chapter 10 > Lesson 10.1.3 > Problem 10-41


The current in a straight river is flowing so that if a motorboat travels upstream at an angle of with a velocity of km/hr, it will land at a spot on the opposite shore directly opposite its starting point. Find the speed of the current.

Draw a diagram.

Right triangle comprised of rays, horizontal ray points right, labeled actual path of motorboat, vertical ray points down, labeled current, hypotenuse points up & right labeled 15 kilometers per hour, angle opposite vertical leg, labeled 20 degrees.

Use trigonometry to solve for the 'current'.