Math Problem Statement

Find all values of x such that sin(2x) = sin(x) and
0 ≀ x ≀ 2πœ‹.

Solution

To find all values of xx such that sin⁑(2x)=sin⁑(x)\sin(2x) = \sin(x) within the interval 0≀x≀2Ο€0 \leq x \leq 2\pi, we will proceed by solving the equation.

Step 1: Use the identity for sin⁑(2x)\sin(2x)

We know that: sin⁑(2x)=2sin⁑(x)cos⁑(x)\sin(2x) = 2\sin(x)\cos(x) So, the equation becomes: 2sin⁑(x)cos⁑(x)=sin⁑(x)2\sin(x)\cos(x) = \sin(x)

Step 2: Factor the equation

We can factor the equation as: sin⁑(x)β‹…(2cos⁑(x)βˆ’1)=0\sin(x) \cdot (2\cos(x) - 1) = 0 This equation is satisfied when either:

  1. sin⁑(x)=0\sin(x) = 0
  2. 2cos⁑(x)βˆ’1=02\cos(x) - 1 = 0

Step 3: Solve for xx from each factor

Case 1: sin⁑(x)=0\sin(x) = 0

sin⁑(x)=0\sin(x) = 0 within 0≀x≀2Ο€0 \leq x \leq 2\pi at: x=0,Ο€,2Ο€x = 0, \pi, 2\pi

Case 2: 2cos⁑(x)βˆ’1=02\cos(x) - 1 = 0

Solve for cos⁑(x)\cos(x): 2cos⁑(x)βˆ’1=0β€…β€ŠβŸΉβ€…β€Šcos⁑(x)=122\cos(x) - 1 = 0 \implies \cos(x) = \frac{1}{2} cos⁑(x)=12\cos(x) = \frac{1}{2} within 0≀x≀2Ο€0 \leq x \leq 2\pi at: x=Ο€3,5Ο€3x = \frac{\pi}{3}, \frac{5\pi}{3}

Step 4: Combine all solutions

The values of xx that satisfy sin⁑(2x)=sin⁑(x)\sin(2x) = \sin(x) within the interval 0≀x≀2Ο€0 \leq x \leq 2\pi are: x=0,Ο€3,Ο€,5Ο€3,2Ο€x = 0, \frac{\pi}{3}, \pi, \frac{5\pi}{3}, 2\pi

Would you like to go over any of these steps in more detail?

Here are some related questions you might find helpful:

  1. How do you solve trigonometric equations involving multiple angles?
  2. What are the general solutions for sin⁑(x)=0\sin(x) = 0 and cos⁑(x)=12\cos(x) = \frac{1}{2}?
  3. How can you use trigonometric identities to simplify equations?
  4. What other identities could be useful in solving trigonometric equations?
  5. How can you verify the solutions of trigonometric equations within a specific interval?

Tip: When solving trigonometric equations, always consider the interval given and ensure that all solutions lie within that interval.

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Trigonometric Identities
Equations

Formulas

Double-angle identity for sine: sin(2x) = 2sin(x)cos(x)

Theorems

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Suitable Grade Level

Grades 11-12