L1 The Sine Law
Completion requirements
Unit A: Geometry
Chapter 3: Trigonometry
In Chapter 1, Lesson 2, triangles were introduced. Triangles are often used in construction, industrial, commercial, and artistic applications. In this lesson, the sine law will be used to solve problems involving triangles.
Edmonton City Hall
The triangle in the diagram of the river is oblique. Oblique triangles can be acute or obtuse, and they do not contain any right angles.
A surveying team would like to build a bridge from point P on the south shore of the river to point R on the north shore. The surveyors were able to measure the angles and side length, as shown in the diagram. Based on these measurements, is it possible to calculate the length of the bridge?
Once the surveyors know the measure of certain angles and distances, trigonometry can be used to find other angles and distances that cannot be measured or are difficult to measure.
A surveying team would like to build a bridge from point P on the south shore of the river to point R on the north shore. The surveyors were able to measure the angles and side length, as shown in the diagram. Based on these measurements, is it possible to calculate the length of the bridge?
Once the surveyors know the measure of certain angles and distances, trigonometry can be used to find other angles and distances that cannot be measured or are difficult to measure.
In this lesson, it will be demonstrated how the sine law can be used to calculate unknown side lengths and angles in an
oblique triangle.
By the end of this lesson, you will be able to
- find a side length in a triangle using the sine law
- find an angle in a triangle using the sine law