How to Find the Angle Given the Cosine Inverse of a Value on the Unit Circle

The video tutorial explains how to solve trigonometric equations by using inverse functions, specifically focusing on the cosine function. It guides students through the process of finding angles using the unit circle and special right triangles, emphasizing the importance of reference angles and restrictions. The tutorial also covers how to identify valid angles when given specific cosine values, using both radians and degrees.

What is the inverse function used to solve for an angle when given a cosine value?

• Cosine inverse

• Sine inverse

• Secant inverse

• Tangent inverse

In the unit circle, what is the reference angle when cosine equals sqrt(3)/2?

• π/4

• π/3

• π/6

• π/2

Which of the following is a special right triangle ratio for cosine?

• 3/2

• sqrt(3)/2

• 1/2

• sqrt(2)/2

What is the angle in radians when the cosine value is negative and the reference angle is π/6?

• 5π/6

• 7π/6

• 11π/6

• π/3

If the reference angle is 30 degrees, what is the angle in degrees when the cosine value is negative?

• 330 degrees

• 210 degrees

• 150 degrees

• 120 degrees