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

8-155.
  1. For each equation, find two solutions 0 ≤ x < 2π, which make the equation true. No calculator should be necessary. Homework Help ✎

    1. cos x = −

    2. tan x =

    3. sin x = 0

    4. cos 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.