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Cogito

Trigonometry · Chapter 5 · Lesson 3

Practice Worksheet

Even, Odd, and Cofunction Identities

What symmetry gives you for free.

12 problems · about 20 minutes · F-TF.C.8, F-TF.A.4

NameDate

Figure — use these to answer the problems

Compare 50° with 310°, which is −50°. One coordinate holds; the other flips.
(0.643, 0.766)
  • Angle50° = π/4 rad
  • x-coordinate0.643
  • y-coordinate0.766
  • cos 50°0.643
  • sin 50°0.766
Angle in degrees50
Figure 1

Warm Up

Straightforward practice. Get the method working first.

5 problems

  1. sin θ = 0.9. What is sin(−θ)?

    Answer

  2. Which function is even?

    • Cosine.
    • Sine.

  3. cos θ = 0.7. What is cos(−θ)?

    Answer

  4. tan θ = 3. What is tan(−θ)?

    Answer

  5. cos 20° ≈ 0.94. What is sin 70°?

    Answer

Build It Up

The same ideas with more to keep track of.

3 problems

  1. sin(−30°) as a decimal?

    Answer

  2. cos(−60°) as a decimal?

    Answer

  3. If sin θ = cos 40°, what is θ in degrees?

    Answer

Stretch Yourself

Mixed problems. Work out what kind of question it is before you start.

4 problems

  1. Which of these functions are odd?

    • sine
    • tangent
    • cosine
    • secant
    • Tick every box that applies.

  2. tan(−45°) as a decimal?

    Answer

  3. The Flip

    sin θ = 0.4. What is sin(−θ)?

    Answer

  4. The Complement

    sin 25° ≈ 0.423. What is cos 65°?

    Answer