Math Problem Statement

Find all solutions of the equation \( \cos x = \sqrt{1 - \sin x} \) in the interval \([0, 2\pi]\).

Solution

The problem asks you to find all solutions to the equation:

cosx=1sinx\cos x = \sqrt{1 - \sin x}

over the interval [0,2π][0, 2\pi].

Step-by-Step Solution

  1. Square Both Sides: To eliminate the square root, square both sides: cos2x=1sinx\cos^2 x = 1 - \sin x

  2. Use the Pythagorean Identity: Recall that cos2x=1sin2x\cos^2 x = 1 - \sin^2 x. Substitute this identity: 1sin2x=1sinx1 - \sin^2 x = 1 - \sin x

  3. Simplify the Equation: Rearrange the equation by moving all terms involving sinx\sin x to one side: sin2xsinx=0\sin^2 x - \sin x = 0

  4. Factor the Equation: Factor out sinx\sin x: sinx(sinx1)=0\sin x (\sin x - 1) = 0

  5. Solve for sinx\sin x: This gives two cases:

    • Case 1: sinx=0\sin x = 0
    • Case 2: sinx=1\sin x = 1
  6. Find xx for Each Case:

    • For sinx=0\sin x = 0, x=0x = 0 and x=πx = \pi.
    • For sinx=1\sin x = 1, x=π2x = \frac{\pi}{2}.

Final Answer

The solutions to the equation in the interval [0,2π][0, 2\pi] are: x=0,π2,πx = 0, \frac{\pi}{2}, \pi

These values should be entered as 0,π2,π0, \frac{\pi}{2}, \pi in terms of π\pi.

Would you like a more detailed breakdown of any of these steps?


Here are 5 related questions for further exploration:

  1. How would the solutions change if the interval were different, such as [0,π][0, \pi]?
  2. What if the equation were cosx=1sinx\cos x = -\sqrt{1 - \sin x} instead? How would that impact the solution?
  3. Why is squaring both sides of an equation a valid approach, and what precautions should you take when using it?
  4. What are the general solutions for sinx=0\sin x = 0 and sinx=1\sin x = 1 beyond the interval [0,2π][0, 2\pi]?
  5. How does the Pythagorean identity relate to other trigonometric identities?

Tip: When solving trigonometric equations, always check for extraneous solutions, especially when squaring both sides.

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Pythagorean Identity
Solving Trigonometric Equations

Formulas

Pythagorean Identity: \( \cos^2 x + \sin^2 x = 1 \)

Theorems

Pythagorean Identity

Suitable Grade Level

Grades 10-12