Math CentralQuandaries & Queries


Question from mary, a teacher:

I have an angle of 72 degrees and each of the sides are 5' long. What is the distance from each of the ends of the 5 feet to form a triangle.

Hi Mary. You can use the Law of Cosines to solve this problem.

This states that in any triangle

c2 = a2 + b2 - 2ab Cos(C)

where a and b are the two sides connecting at angle C and c is the third side (opposite angle C). Put in the values you are given and you can find the length of the side you need.

Stephen La Rocque

About Math Central


Math Central is supported by the University of Regina and The Pacific Institute for the Mathematical Sciences.
Quandaries & Queries page Home page University of Regina PIMS