### Home > CCA2 > Chapter 8 > Lesson 8.3.2 > Problem 8-155

8-155.

For each equation, find two solutions 0 ≤ **x****< 2****π****, which make the equation true. No calculator should be necessary. Homework Help ✎****cos****x****= −**tan

*x*=sin

*x*= 0cos

*x*=

In which quadrants is cosine negative? Sketch a unit circle with right triangles with 30° angles at the origin in the second and third quadrants. What are the circular angles?

*x* = 120° and 240°

Now convert the angles into radians.

See part (a).

If sin(*x*) = 0, *x* = 0.

*x* = 0

Remember the side ratios of 45° right triangles.