Martina wants to know the length of a tunnel built through a

Martina wants to know the length of a tunnel built through a mountain. To do so, she makes the measurements shown in the figure below. Use these measurements to find the length of the tunnel. Carry your intermediate computations to at least four decimal places. Round your answer to the nearest tenth of a meter.

Solution

We have to use law of cosine here. Let d is the length of the tunnel

d²= 22²+129²-2(222)(129)cos82

d²= 65925- 57276 cos 82

d=240.7 m