Lesson 6

In Try This 2, you may have found that the sine law can be used to determine unknown lengths of a triangle. The two versions of the sine law you would use to solve for the lengh of the side between A and B are or . This is because the values A, a, and C are given and you want to determine c.

The following example shows how the triangle from Try This 1 can be used to solve a different problem.

Khadija wants to build a walkway from her back door to a shed at the back of her yard. She needs to provide the length of the proposed walkway to a contractor in order to get a phone estimate for the cost. She knows her house is 10.7 m wide and has measured two angles, as shown in the diagram.

Khadija can use the sine law to determine the distance from her house to the shed (d on the diagram). Watch the solution in Determining a Distance Using the Sine Law. Pay attention to how substitution is used with the sine law.