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Exact values of inverse trig functions practice problems

Exact values of arcsin, arccos and arctan, inside their restricted ranges. 25 problems with worked solutions; in 25 of them every equation is proved by a computer algebra system.

16 worked problems

Try each one before opening the solution. Every line is labeled with what checked it. How we verify

Find the exact value of \( \displaystyle \arcsin{\left(-1 \right)} \).
  1. arcsin returns the one angle in [−π/2, π/2] whose sin is -1.
    Reviewed
  2. \[ \sin{\left(\frac{\left(-1\right) \pi}{2} \right)} = -1 \]
    sin(-pi/2) = -1, and -pi/2 is in [−π/2, π/2].✓ Proved
  3. \[ \operatorname{asin}{\left(-1 \right)} = - \frac{\pi}{2} \]
    So that angle is the value.✓ Proved
Answer \( - \frac{\pi}{2} \)

✓ Nihil obstat Lines: 2 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt · How we verify

Find the exact value of \( \displaystyle \arctan{\left(\sqrt{3} \right)} \).
  1. arctan returns the one angle in (−π/2, π/2) whose tan is sqrt(3).
    Reviewed
  2. \[ \tan{\left(\frac{\pi}{3} \right)} = \sqrt{3} \]
    tan(pi/3) = sqrt(3), and pi/3 is in (−π/2, π/2).✓ Proved
  3. \[ \operatorname{atan}{\left(\sqrt{3} \right)} = \frac{\pi}{3} \]
    So that angle is the value.✓ Proved
Answer \( \frac{\pi}{3} \)

✓ Nihil obstat Lines: 2 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt · How we verify

Find the exact value of \( \displaystyle \arctan{\left(0 \right)} \).
  1. arctan returns the one angle in (−π/2, π/2) whose tan is 0.
    Reviewed
  2. \[ \tan{\left(0 \right)} = 0 \]
    tan(0) = 0, and 0 is in (−π/2, π/2).✓ Proved
  3. \[ \operatorname{atan}{\left(0 \right)} = 0 \]
    So that angle is the value.✓ Proved
Answer \( 0 \)

✓ Nihil obstat Lines: 2 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt · How we verify

Find the exact value of \( \displaystyle \arccos{\left(- \frac{\sqrt{2}}{2} \right)} \).
  1. arccos returns the one angle in [0, π] whose cos is -sqrt(2)/2.
    Reviewed
  2. \[ \cos{\left(\frac{3 \pi}{4} \right)} = - \frac{\sqrt{2}}{2} \]
    cos(3*pi/4) = -sqrt(2)/2, and 3*pi/4 is in [0, π].✓ Proved
  3. \[ \operatorname{acos}{\left(\frac{\left(-1\right) \sqrt{2}}{2} \right)} = \frac{3 \pi}{4} \]
    So that angle is the value.✓ Proved
Answer \( \frac{3 \pi}{4} \)

✓ Nihil obstat Lines: 2 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt · How we verify

Find the exact value of \( \displaystyle \arccos{\left(-1 \right)} \).
  1. arccos returns the one angle in [0, π] whose cos is -1.
    Reviewed
  2. \[ \cos{\left(\pi \right)} = -1 \]
    cos(pi) = -1, and pi is in [0, π].✓ Proved
  3. \[ \operatorname{acos}{\left(-1 \right)} = \pi \]
    So that angle is the value.✓ Proved
Answer \( \pi \)

✓ Nihil obstat Lines: 2 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt · How we verify

Find the exact value of \( \displaystyle \arctan{\left(\frac{\sqrt{3}}{3} \right)} \).
  1. arctan returns the one angle in (−π/2, π/2) whose tan is sqrt(3)/3.
    Reviewed
  2. \[ \tan{\left(\frac{\pi}{6} \right)} = \frac{\sqrt{3}}{3} \]
    tan(pi/6) = sqrt(3)/3, and pi/6 is in (−π/2, π/2).✓ Proved
  3. \[ \operatorname{atan}{\left(\frac{\sqrt{3}}{3} \right)} = \frac{\pi}{6} \]
    So that angle is the value.✓ Proved
Answer \( \frac{\pi}{6} \)

✓ Nihil obstat Lines: 2 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt · How we verify

Find the exact value of \( \displaystyle \arcsin{\left(1 \right)} \).
  1. arcsin returns the one angle in [−π/2, π/2] whose sin is 1.
    Reviewed
  2. \[ \sin{\left(\frac{\pi}{2} \right)} = 1 \]
    sin(pi/2) = 1, and pi/2 is in [−π/2, π/2].✓ Proved
  3. \[ \operatorname{asin}{\left(1 \right)} = \frac{\pi}{2} \]
    So that angle is the value.✓ Proved
Answer \( \frac{\pi}{2} \)

✓ Nihil obstat Lines: 2 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt · How we verify

Find the exact value of \( \displaystyle \arctan{\left(- \frac{\sqrt{3}}{3} \right)} \).
  1. arctan returns the one angle in (−π/2, π/2) whose tan is -sqrt(3)/3.
    Reviewed
  2. \[ \tan{\left(\frac{\left(-1\right) \pi}{6} \right)} = - \frac{\sqrt{3}}{3} \]
    tan(-pi/6) = -sqrt(3)/3, and -pi/6 is in (−π/2, π/2).✓ Proved
  3. \[ \operatorname{atan}{\left(\frac{\left(-1\right) \sqrt{3}}{3} \right)} = - \frac{\pi}{6} \]
    So that angle is the value.✓ Proved
Answer \( - \frac{\pi}{6} \)

✓ Nihil obstat Lines: 2 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt · How we verify

Find the exact value of \( \displaystyle \arccos{\left(- \frac{1}{2} \right)} \).
  1. arccos returns the one angle in [0, π] whose cos is -1/2.
    Reviewed
  2. \[ \cos{\left(\frac{2 \pi}{3} \right)} = - \frac{1}{2} \]
    cos(2*pi/3) = -1/2, and 2*pi/3 is in [0, π].✓ Proved
  3. \[ \operatorname{acos}{\left(- \frac{1}{2} \right)} = \frac{2 \pi}{3} \]
    So that angle is the value.✓ Proved
Answer \( \frac{2 \pi}{3} \)

✓ Nihil obstat Lines: 2 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt · How we verify

Find the exact value of \( \displaystyle \arccos{\left(\frac{\sqrt{3}}{2} \right)} \).
  1. arccos returns the one angle in [0, π] whose cos is sqrt(3)/2.
    Reviewed
  2. \[ \cos{\left(\frac{\pi}{6} \right)} = \frac{\sqrt{3}}{2} \]
    cos(pi/6) = sqrt(3)/2, and pi/6 is in [0, π].✓ Proved
  3. \[ \operatorname{acos}{\left(\frac{\sqrt{3}}{2} \right)} = \frac{\pi}{6} \]
    So that angle is the value.✓ Proved
Answer \( \frac{\pi}{6} \)

✓ Nihil obstat Lines: 2 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt · How we verify

Find the exact value of \( \displaystyle \arctan{\left(- \sqrt{3} \right)} \).
  1. arctan returns the one angle in (−π/2, π/2) whose tan is -sqrt(3).
    Reviewed
  2. \[ \tan{\left(\frac{\left(-1\right) \pi}{3} \right)} = - \sqrt{3} \]
    tan(-pi/3) = -sqrt(3), and -pi/3 is in (−π/2, π/2).✓ Proved
  3. \[ \operatorname{atan}{\left(- \sqrt{3} \right)} = - \frac{\pi}{3} \]
    So that angle is the value.✓ Proved
Answer \( - \frac{\pi}{3} \)

✓ Nihil obstat Lines: 2 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt · How we verify

Find the exact value of \( \displaystyle \arcsin{\left(- \frac{1}{2} \right)} \).
  1. arcsin returns the one angle in [−π/2, π/2] whose sin is -1/2.
    Reviewed
  2. \[ \sin{\left(\frac{\left(-1\right) \pi}{6} \right)} = - \frac{1}{2} \]
    sin(-pi/6) = -1/2, and -pi/6 is in [−π/2, π/2].✓ Proved
  3. \[ \operatorname{asin}{\left(- \frac{1}{2} \right)} = - \frac{\pi}{6} \]
    So that angle is the value.✓ Proved
Answer \( - \frac{\pi}{6} \)

✓ Nihil obstat Lines: 2 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt · How we verify

Find the exact value of \( \displaystyle \arcsin{\left(\frac{\sqrt{3}}{2} \right)} \).
  1. arcsin returns the one angle in [−π/2, π/2] whose sin is sqrt(3)/2.
    Reviewed
  2. \[ \sin{\left(\frac{\pi}{3} \right)} = \frac{\sqrt{3}}{2} \]
    sin(pi/3) = sqrt(3)/2, and pi/3 is in [−π/2, π/2].✓ Proved
  3. \[ \operatorname{asin}{\left(\frac{\sqrt{3}}{2} \right)} = \frac{\pi}{3} \]
    So that angle is the value.✓ Proved
Answer \( \frac{\pi}{3} \)

✓ Nihil obstat Lines: 2 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt · How we verify

Find the exact value of \( \displaystyle \arctan{\left(-1 \right)} \).
  1. arctan returns the one angle in (−π/2, π/2) whose tan is -1.
    Reviewed
  2. \[ \tan{\left(\frac{\left(-1\right) \pi}{4} \right)} = -1 \]
    tan(-pi/4) = -1, and -pi/4 is in (−π/2, π/2).✓ Proved
  3. \[ \operatorname{atan}{\left(-1 \right)} = - \frac{\pi}{4} \]
    So that angle is the value.✓ Proved
Answer \( - \frac{\pi}{4} \)

✓ Nihil obstat Lines: 2 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt · How we verify

Find the exact value of \( \displaystyle \arccos{\left(\frac{1}{2} \right)} \).
  1. arccos returns the one angle in [0, π] whose cos is 1/2.
    Reviewed
  2. \[ \cos{\left(\frac{\pi}{3} \right)} = \frac{1}{2} \]
    cos(pi/3) = 1/2, and pi/3 is in [0, π].✓ Proved
  3. \[ \operatorname{acos}{\left(1 \cdot \frac{1}{2} \right)} = \frac{\pi}{3} \]
    So that angle is the value.✓ Proved
Answer \( \frac{\pi}{3} \)

✓ Nihil obstat Lines: 2 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt · How we verify

Find the exact value of \( \displaystyle \arcsin{\left(- \frac{\sqrt{2}}{2} \right)} \).
  1. arcsin returns the one angle in [−π/2, π/2] whose sin is -sqrt(2)/2.
    Reviewed
  2. \[ \sin{\left(\frac{\left(-1\right) \pi}{4} \right)} = - \frac{\sqrt{2}}{2} \]
    sin(-pi/4) = -sqrt(2)/2, and -pi/4 is in [−π/2, π/2].✓ Proved
  3. \[ \operatorname{asin}{\left(\frac{\left(-1\right) \sqrt{2}}{2} \right)} = - \frac{\pi}{4} \]
    So that angle is the value.✓ Proved
Answer \( - \frac{\pi}{4} \)

✓ Nihil obstat Lines: 2 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt · How we verify

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