Math Problem Statement

Cos[sin^-1(- sqrt3/2)]

Solution

To find the value of cos(sin1(32))\cos\left(\sin^{-1}\left(-\frac{\sqrt{3}}{2}\right)\right), let's break it down step by step.

Step 1: Interpret the inverse sine

We are given sin1(32)\sin^{-1}\left(-\frac{\sqrt{3}}{2}\right), which is the angle θ\theta such that:

sin(θ)=32\sin(\theta) = -\frac{\sqrt{3}}{2}

We need to determine the angle θ\theta that satisfies this equation. The sine function sin(θ)=32\sin(\theta) = -\frac{\sqrt{3}}{2} occurs at specific angles, and we know that:

sin(π3)=32\sin\left(-\frac{\pi}{3}\right) = -\frac{\sqrt{3}}{2}

Thus, the angle θ=π3\theta = -\frac{\pi}{3}.

Step 2: Find cos(θ)\cos(\theta)

Next, we want to find cos(sin1(32))=cos(π3)\cos\left(\sin^{-1}\left(-\frac{\sqrt{3}}{2}\right)\right) = \cos\left(-\frac{\pi}{3}\right).

Using the property of cosine that cos(θ)=cos(θ)\cos(-\theta) = \cos(\theta), we have:

cos(π3)=cos(π3)\cos\left(-\frac{\pi}{3}\right) = \cos\left(\frac{\pi}{3}\right)

The cosine of π3\frac{\pi}{3} is:

cos(π3)=12\cos\left(\frac{\pi}{3}\right) = \frac{1}{2}

Thus,

cos(sin1(32))=12\cos\left(\sin^{-1}\left(-\frac{\sqrt{3}}{2}\right)\right) = \frac{1}{2}

Final Answer:

cos(sin1(32))=12\cos\left(\sin^{-1}\left(-\frac{\sqrt{3}}{2}\right)\right) = \frac{1}{2}


Would you like further details or have any questions about this process?

Here are five related questions:

  1. How do you find cos(sin1(x))\cos\left(\sin^{-1}(x)\right) for any value of xx?
  2. How do inverse trigonometric functions work in general?
  3. What is the significance of sin1(x)\sin^{-1}(x) and its range?
  4. Can you solve for cos(sin1(x))\cos\left(\sin^{-1}(x)\right) when xx is positive?
  5. How does the unit circle help in evaluating inverse trigonometric functions?

Tip: When working with inverse trigonometric functions, remember that the range of sin1(x)\sin^{-1}(x) is restricted to π2θπ2-\frac{\pi}{2} \leq \theta \leq \frac{\pi}{2}, which helps determine the correct quadrant for the angle.

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Inverse Trigonometric Functions
Unit Circle Properties

Formulas

cos(θ) = cos(-θ)
cos²(θ) + sin²(θ) = 1

Theorems

Pythagorean Identity
Properties of Inverse Trigonometric Functions

Suitable Grade Level

Grades 10-12