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

8-155.

For each equation, find two solutions , which make the equation true. No calculator should be necessary.  

Compute without a calculator

  1. Recall that  so the reference angle will be .

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

    and

    Now convert the angles into radians.

  1. See part (a).

  1. If , .

  1. Remember the side ratios of right triangles.