Objectives
- Solve Trigonometric Equations using exact values for 30, 45, and 60 degree angles and angles with 30, 45 or 60 degree reference angles.
- Solve Trigonometric Equations using your calculator for other angle measurements.
Lesson Overview
We are skipping lesson 6.4 for now – we will come back to it later. In this lesson you are solving trigonometric equations. The difference between solving trigonometric equations and proving trigonometric identities is that identities are always true statements – so we can prove them for any x-value. Solving trigonometric equations, however, involves finding the specific x-values that make the statement true.
Think back to the good old Algebra days. An example of an “Algebra Identity” would be 2x = 2x. This is an always true statement. It works for any x-value. On the other hand, the equation 2x +5 = 9 is not always true. It is only true for a specific value of x (x = 2, to be exact).
So in this lesson you are solving equations like our 2x + 5 = 9, but adding in the trig element. Here are a few things to keep in mind when solving problems:
- If a trig equation is quadratic, factor or use the quadratic equation (Examples 5, 6, 7)
- If a trig equation involves more than one function (sine and cosine, for example), see if you can use identities to re-write the equation in terms of only one function (Examples 9 – 11)
Study Materials
Video 1: Intro and Basic Examples (Examples 1 & 2)
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Video 2: Solving for “2x” and using your calculator (Examples 3 & 4)
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Video 3: Pythagorean Examples (Examples 5 – 7)
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