Math Problem Statement

cos(sin−1(square root 3/2))

Solution

We are tasked with evaluating cos(sin1(32))\cos\left(\sin^{-1}\left(\frac{\sqrt{3}}{2}\right)\right).

Step-by-step Solution:

  1. Interpret the problem:
    The expression sin1(32)\sin^{-1}\left(\frac{\sqrt{3}}{2}\right) represents an angle θ\theta, where: sin(θ)=32.\sin(\theta) = \frac{\sqrt{3}}{2}. From trigonometry, θ\theta lies in the range π2-\frac{\pi}{2} to π2\frac{\pi}{2} for the inverse sine function.

  2. Identify the reference angle:
    From basic trigonometric values, sin(θ)=32\sin(\theta) = \frac{\sqrt{3}}{2} corresponds to θ=π3\theta = \frac{\pi}{3}.

  3. Use the Pythagorean identity:
    We need to find cos(θ)\cos(\theta). Using the Pythagorean identity: sin2(θ)+cos2(θ)=1.\sin^2(\theta) + \cos^2(\theta) = 1. Substitute sin(θ)=32\sin(\theta) = \frac{\sqrt{3}}{2}: (32)2+cos2(θ)=1.\left(\frac{\sqrt{3}}{2}\right)^2 + \cos^2(\theta) = 1. 34+cos2(θ)=1.\frac{3}{4} + \cos^2(\theta) = 1. cos2(θ)=134=14.\cos^2(\theta) = 1 - \frac{3}{4} = \frac{1}{4}. cos(θ)=±12.\cos(\theta) = \pm\frac{1}{2}.

  4. Determine the sign of cos(θ)\cos(\theta):
    Since sin1\sin^{-1} always gives angles in the first or fourth quadrant (where cosine is non-negative), we take: cos(θ)=12.\cos(\theta) = \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 more details or have any questions? Here are some related topics you might find interesting:

  1. What are the ranges of inverse trigonometric functions?
  2. How is the Pythagorean identity derived?
  3. Why is the cosine positive in the first and fourth quadrants?
  4. How do you simplify other expressions involving inverse trig functions?
  5. What are the exact values of all six trigonometric functions at common angles?

Tip: Always sketch a triangle when working with inverse trig functions to visualize the relationships easily!

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Trigonometry
Inverse Trigonometric Functions
Pythagorean Identity

Formulas

Pythagorean Identity: sin^2(θ) + cos^2(θ) = 1
Inverse Sine: sin^(-1)(x)

Theorems

Pythagorean Theorem

Suitable Grade Level

Grades 10-12