What is the purpose of using inverse trigonometric functions?

To find the measure of an angle in a right triangle when you know the ratio of two of its sides.

Explain the relationship between a trigonometric function (e.g., cosine) and its inverse (e.g., cosine inverse).

They are opposite operations that undo each other. If you take the cosine of an angle and then take the cosine inverse of the result, you get back the original angle.

You are given a right triangle where the opposite side to an angle is 7 and the adjacent side is 7. Set up the inverse trigonometric function you would use to find the angle, and then determine the angle in degrees.

Tangent inverse of 7/7 = 45 degrees

Finding Angles with Inverse Trig

Grade 9th Grade · Math · 45 min

What's Included

Learning Objective

I can evaluate inverse trigonometric functions to find angles.

Warm-Up Video

Kristen Watson · 6:43

Inverse Trig. For Right Triangles

Guided Notes

3 key concepts

1
Inverse trigonometric functions are used to solve for missing angles of right triangles.
2
The inverse of cosine is cosine inverse, the inverse of sine is sine inverse, and the inverse of tangent is tangent inverse.
3
When using inverse trig functions, it is important to ensure your calculator is set to degrees mode.

Practice Questions

9 questions · Multiple choice & Short answer

Exit Ticket

Quick comprehension check

“In a right triangle, the side opposite an angle is 15 cm and the hypotenuse is 17 cm. What is the measure of the angle in degrees? Show your work.”

Complete Lesson Package

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Finding Angles with Inverse Trig

What's Included

Learning Objective

Warm-Up Video

Guided Notes

Practice Questions

Exit Ticket

Complete Lesson Package

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