Hey, everyone. In this problem, we're asked to evaluate the expression the inverse cosine of negative root 3 over 2. Now, whenever working with an inverse trigonometric function, remember that we can also think of this as OK, the cosine of what angle is equal to negative root 3 over 2, and we want to find the angle for which that is true. Now, when working with the inverse cosine, we know that our angles can only be between 0 and π. But we can actually get even more specific here because we know that all our cosine values are going to be positive in quadrant 1, and all our cosine values in quadrant 2 are going to be negative. So whenever we're taking the inverse cosine of a positive number, we know that our solution has to be in quadrant 1. And whenever we're taking the inverse cosine of a negative number, just like we are here, we know that our solution has to be in quadrant 2. So here, we already know that our angle has to be in this second quadrant. So for which one of these angles is the cosine equal to negative root 3 over 2? Well, I know that the cosine of 5π over 6 is equal to just that so that represents my solution. My angle here is 5π over 6, and we are done here. Thanks for watching and I'll see you in the next one.
Table of contents
- 0. Review of College Algebra4h 43m
- 1. Measuring Angles39m
- 2. Trigonometric Functions on Right Triangles2h 5m
- 3. Unit Circle1h 19m
- 4. Graphing Trigonometric Functions1h 19m
- 5. Inverse Trigonometric Functions and Basic Trigonometric Equations1h 41m
- 6. Trigonometric Identities and More Equations2h 34m
- 7. Non-Right Triangles1h 38m
- 8. Vectors2h 25m
- 9. Polar Equations2h 5m
- 10. Parametric Equations1h 6m
- 11. Graphing Complex Numbers1h 7m
5. Inverse Trigonometric Functions and Basic Trigonometric Equations
Inverse Sine, Cosine, & Tangent
Video duration:
1mPlay a video:
Related Videos
Related Practice
Inverse Sine, Cosine, & Tangent practice set
- Problem sets built by lead tutorsExpert video explanations