Trig identities: Pythagorean, symmetry and periodicity, and sum and difference

Grade 11 Math Worksheet

NameDate

Circle the best answer, or write your answer on the line.

  1. On Ren's unit circle worksheet, θ is in Quadrant IV and sin θ = -7/25. What is cos θ?

  2. Tala's robot ends a turn θ in Quadrant III with cos θ = -9/41. What is sin θ?

  3. On Zee's unit circle worksheet, θ is in Quadrant II and sin θ = 11/61. What is tan θ?

  4. Esme's robot ends a turn θ in Quadrant III with cos θ = -33/65. What is tan θ?

  5. Jun writes sin 75° = sin(45° + 30°) = sin 45° cos 30° + cos 45° sin 30° on a worksheet. Which is the exact value of sin 75°?

    • (√6 − √2)/4
    • (√6 + √2)/4
    • √2/2
    • (√2 + 1)/2
  6. Kira writes cos 15° = cos(45° − 30°) = cos 45° cos 30° + sin 45° sin 30° from a math book. Which is the exact value of cos 15°?

    • (√6 + √2)/4
    • (√6 − √2)/4
    • √2/2
    • (√2 − √3)/2
  7. Luz writes sin 15° = sin(45° − 30°) = sin 45° cos 30° − cos 45° sin 30° on a worksheet. Which is the exact value of sin 15°?

    • (√6 + √2)/4
    • √2/2
    • (√2 − 1)/2
    • (√6 − √2)/4
  8. On Noah's unit circle worksheet, the turn θ ends at (12/13, -5/13). What is sin(-θ) + cos(-θ)?

  9. Pia's robot ends a turn θ at (-8/17, 15/17) on a unit circle floor grid. What is sin(-θ) − cos(-θ)?

  10. Tala's robot ends a turn θ at (9/41, 40/41) on a unit circle floor grid. What is sin(θ + 2π) + cos(-θ)?

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Trig identities: Pythagorean, symmetry and periodicity, and sum and difference

Answer Key - Grade 11 Math Worksheet

Circle the best answer, or write your answer on the line.

  1. On Ren's unit circle worksheet, θ is in Quadrant IV and sin θ = -7/25. What is cos θ?

    24/25
  2. Tala's robot ends a turn θ in Quadrant III with cos θ = -9/41. What is sin θ?

    -40/41
  3. On Zee's unit circle worksheet, θ is in Quadrant II and sin θ = 11/61. What is tan θ?

    -11/60
  4. Esme's robot ends a turn θ in Quadrant III with cos θ = -33/65. What is tan θ?

    56/33
  5. Jun writes sin 75° = sin(45° + 30°) = sin 45° cos 30° + cos 45° sin 30° on a worksheet. Which is the exact value of sin 75°?

    • (√6 − √2)/4
    • (√6 + √2)/4
    • √2/2
    • (√2 + 1)/2
  6. Kira writes cos 15° = cos(45° − 30°) = cos 45° cos 30° + sin 45° sin 30° from a math book. Which is the exact value of cos 15°?

    • (√6 + √2)/4
    • (√6 − √2)/4
    • √2/2
    • (√2 − √3)/2
  7. Luz writes sin 15° = sin(45° − 30°) = sin 45° cos 30° − cos 45° sin 30° on a worksheet. Which is the exact value of sin 15°?

    • (√6 + √2)/4
    • √2/2
    • (√2 − 1)/2
    • (√6 − √2)/4
  8. On Noah's unit circle worksheet, the turn θ ends at (12/13, -5/13). What is sin(-θ) + cos(-θ)?

    17/13
  9. Pia's robot ends a turn θ at (-8/17, 15/17) on a unit circle floor grid. What is sin(-θ) − cos(-θ)?

    -7/17
  10. Tala's robot ends a turn θ at (9/41, 40/41) on a unit circle floor grid. What is sin(θ + 2π) + cos(-θ)?

    49/41