Topic: Oblique Triangles and the Laws
Subtopic: Law of Sines
Overview
All the trig we have done so far in the course has been "right angle trig" where we required a right triangle before we could set-up and use any of the six trig functions. In this chapter we learn two laws that enable us to use trig functions on oblique (non-right) triangles. The first of these is the law of sines. It is based on ratios of the sine of an angle and the length of the side opposite that angle.
Depending on the information given, there is usually only one triangle that fits the info. However, sometimes there are two different triangles that could fit the data, or no triangle possible! This is called the ambiguous case. Watch out for it!
Objectives
By the end of this topic you should know and be prepared to be tested on:
- 7.1.1 Know the law of sines formula
- 7.1.2 Understand that the law of sines can be used in cases when the information given is of the form AAS, ASA, or SSA
- 7.1.3 Solve oblique triangles using the law of sines
- 7.1.4 Recognize the ambiguous case (which occurs when given SSA)
- 7.1.5 In the ambiguous case, determine if there is 0, 1, or 2 solution triangles
- 7.1.6 In the ambiguous case, if 2 solution triangles, find both
Terminology
Define: oblique triangle, included side, law of sines, ambiguous case
Supplementary Resources
Need help understanding how to identify AAS, ASA, etc.? Read Help for Oblique Triangles. Explore the Ambiguous Case and how it may have 0, 1, or 2 solutions.