Math Problem Statement

please find the value of sin(2cos^-1((sqrt 2)/2). Please round to two decimal places if needed

Solution

We are asked to find the value of sin(2cos1(22))\sin \left( 2 \cos^{-1} \left( \frac{\sqrt{2}}{2} \right) \right).

Step-by-step solution:

  1. Let θ=cos1(22)\theta = \cos^{-1} \left( \frac{\sqrt{2}}{2} \right).
    This implies that cos(θ)=22\cos(\theta) = \frac{\sqrt{2}}{2}, and we are asked to find sin(2θ)\sin(2\theta).

  2. Use the double-angle identity for sine: sin(2θ)=2sin(θ)cos(θ)\sin(2\theta) = 2 \sin(\theta) \cos(\theta) We already know that cos(θ)=22\cos(\theta) = \frac{\sqrt{2}}{2}, so now we need to find sin(θ)\sin(\theta).

  3. Find sin(θ)\sin(\theta) using the Pythagorean identity: sin2(θ)+cos2(θ)=1\sin^2(\theta) + \cos^2(\theta) = 1 Substituting cos(θ)=22\cos(\theta) = \frac{\sqrt{2}}{2}: sin2(θ)+(22)2=1\sin^2(\theta) + \left( \frac{\sqrt{2}}{2} \right)^2 = 1 sin2(θ)+24=1\sin^2(\theta) + \frac{2}{4} = 1 sin2(θ)+12=1\sin^2(\theta) + \frac{1}{2} = 1 sin2(θ)=112=12\sin^2(\theta) = 1 - \frac{1}{2} = \frac{1}{2} sin(θ)=22\sin(\theta) = \frac{\sqrt{2}}{2} (Note that sin(θ)\sin(\theta) is positive because θ\theta is in the range [0,π][0, \pi], given that cos1\cos^{-1} produces values within this range.)

  4. Now calculate sin(2θ)\sin(2\theta): sin(2θ)=2sin(θ)cos(θ)\sin(2\theta) = 2 \sin(\theta) \cos(\theta) Substituting the values of sin(θ)\sin(\theta) and cos(θ)\cos(\theta): sin(2θ)=2×22×22\sin(2\theta) = 2 \times \frac{\sqrt{2}}{2} \times \frac{\sqrt{2}}{2} sin(2θ)=2×24=1\sin(2\theta) = 2 \times \frac{2}{4} = 1

Final Answer:

The value of sin(2cos1(22))\sin \left( 2 \cos^{-1} \left( \frac{\sqrt{2}}{2} \right) \right) is 1.

Would you like any additional details or clarifications?

Related Questions:

  1. How do we derive the double angle identities for trigonometric functions?
  2. What is the relationship between inverse trigonometric functions and the unit circle?
  3. How does the range of inverse cosine (cos⁻¹) affect the value of sin(θ)\sin(\theta)?
  4. What is the significance of the Pythagorean identity in trigonometry?
  5. How do you find cos1\cos^{-1} of values greater than 1 or less than -1?

Tip: Always ensure to check the domain and range of inverse functions to avoid errors when calculating trigonometric values.

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Inverse Trigonometric Functions
Double Angle Identities

Formulas

sin(2θ) = 2sin(θ)cos(θ)
sin^2(θ) + cos^2(θ) = 1

Theorems

Pythagorean Identity
Double Angle Identity for Sine

Suitable Grade Level

Grades 9-11