Math Problem Statement

Find the exact value of sin^(-1)(sin(5π/6)).

Solution

The problem is asking for the exact value of sin1(sin(5π6))\sin^{-1} \left( \sin \left( \frac{5\pi}{6} \right) \right).

Step-by-Step Solution:

  1. Understanding the inverse sine (arcsine):

    • The function sin1(x)\sin^{-1}(x) (also called arcsine) returns the angle yy such that sin(y)=x\sin(y) = x.
    • The principal range of sin1(x)\sin^{-1}(x) is π2yπ2-\frac{\pi}{2} \leq y \leq \frac{\pi}{2}. This is crucial because arcsine only returns values in this range.
  2. Simplifying sin(5π6)\sin \left( \frac{5\pi}{6} \right):

    • 5π6\frac{5\pi}{6} is in the second quadrant where sine is positive.
    • The reference angle for 5π6\frac{5\pi}{6} is π6\frac{\pi}{6}, so sin(5π6)=sin(π6)=12\sin \left( \frac{5\pi}{6} \right) = \sin \left( \frac{\pi}{6} \right) = \frac{1}{2}.
  3. Finding sin1(12)\sin^{-1} \left( \frac{1}{2} \right):

    • We now need to find the angle θ\theta such that sin(θ)=12\sin(\theta) = \frac{1}{2} and θ\theta lies in the range π2θπ2-\frac{\pi}{2} \leq \theta \leq \frac{\pi}{2}.
    • The angle in this range is π6\frac{\pi}{6}.

Conclusion:

The exact value of sin1(sin(5π6))\sin^{-1} \left( \sin \left( \frac{5\pi}{6} \right) \right) is π6\frac{\pi}{6}.

So, the correct answer is: Aπ6\boxed{A} \quad \frac{\pi}{6}

Would you like more details on inverse trigonometric functions?


Here are 5 related questions for further practice:

  1. What is the value of sin1(sin(7π6))\sin^{-1} \left( \sin \left( \frac{7\pi}{6} \right) \right)?
  2. Simplify sin1(sin(3π4))\sin^{-1} \left( \sin \left( -\frac{3\pi}{4} \right) \right).
  3. What is the principal value of cos1(cos(4π3))\cos^{-1} \left( \cos \left( \frac{4\pi}{3} \right) \right)?
  4. Find tan1(tan(5π4))\tan^{-1} \left( \tan \left( \frac{5\pi}{4} \right) \right).
  5. What is the range of the inverse sine function?

Tip: When solving problems involving inverse trigonometric functions, always pay attention to the principal range of the inverse function.

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Math Problem Analysis

Mathematical Concepts

Inverse Trigonometric Functions
Principal Range of Arcsine
Trigonometric Identities

Formulas

sin^(-1)(x) returns the angle whose sine is x
Principal range of sin^(-1)(x) is -π/2 ≤ y ≤ π/2
Reference angle in trigonometry

Theorems

Inverse Function Theorem

Suitable Grade Level

Grades 11-12