Practice!

Sample Problem

To approximate the length of a pond, you walk 200 ft from point A to point B, turn 80° and

walk 160 ft to point C. Approximate the length AC of the pond. Round your answer to two decimal points.

ft

Solution

First, draw a diagram and use law of Cosines to find AC (aka length b). Angle B is 100° (180°-the 80° you turn at point B).

b2=a2+c2-2accosB=1602+2002-2(160)(200)cos 100°76713.48337

b276.97 ft