Math Problem Statement

1-cos(x)=-sin(x)

Solution

To solve the equation 1cos(x)=sin(x)1 - \cos(x) = -\sin(x), we can proceed with the following steps:

Step 1: Rearrange the equation

The given equation is: 1cos(x)=sin(x)1 - \cos(x) = -\sin(x) Rearrange this to: 1=cos(x)sin(x)1 = \cos(x) - \sin(x)

Step 2: Use trigonometric identity

We can try to express cos(x)sin(x)\cos(x) - \sin(x) in a simpler form using a trigonometric identity. We use the identity for a linear combination of sine and cosine:

cos(x)sin(x)=2cos(x+π4)\cos(x) - \sin(x) = \sqrt{2} \cos\left(x + \frac{\pi}{4}\right) This identity is derived by recognizing that cos(x)sin(x)\cos(x) - \sin(x) can be rewritten as a cosine function with a phase shift.

So, we can rewrite the equation as: 1=2cos(x+π4)1 = \sqrt{2} \cos\left(x + \frac{\pi}{4}\right)

Step 3: Solve for xx

Now, solve for xx: cos(x+π4)=12\cos\left(x + \frac{\pi}{4}\right) = \frac{1}{\sqrt{2}} We know that: cos(π4)=12\cos\left(\frac{\pi}{4}\right) = \frac{1}{\sqrt{2}}

Thus, we can write: x + \frac{\pi}{4} = \pm \frac{\pi}{4} + 2k\pi \quad \text{(where k is any integer)}

Step 4: Solve for xx

Now, solving for xx: x+π4=π4+2kπorx+π4=π4+2kπx + \frac{\pi}{4} = \frac{\pi}{4} + 2k\pi \quad \text{or} \quad x + \frac{\pi}{4} = -\frac{\pi}{4} + 2k\pi Subtracting π4\frac{\pi}{4} from both sides: x=2kπorx=π2+2kπx = 2k\pi \quad \text{or} \quad x = -\frac{\pi}{2} + 2k\pi

Final Answer:

The general solution for xx is: x=2kπorx=π2+2kπx = 2k\pi \quad \text{or} \quad x = -\frac{\pi}{2} + 2k\pi where kk is any integer.

Would you like to explore any specific part of this solution, or do you have any further questions?

Here are 5 related questions:

  1. What is the derivation of the identity cos(x)sin(x)=2cos(x+π4)\cos(x) - \sin(x) = \sqrt{2} \cos\left(x + \frac{\pi}{4}\right)?
  2. How can you solve trigonometric equations involving sine and cosine functions more efficiently?
  3. What is the geometric interpretation of the equation 1cos(x)=sin(x)1 - \cos(x) = -\sin(x)?
  4. How do you handle trigonometric equations involving multiple angles (like cos(2x)\cos(2x))?
  5. What are the periodic properties of sine and cosine functions, and how do they affect the solutions?

Tip: Always try to look for known trigonometric identities to simplify equations before attempting to solve them directly. This can often make the problem much easier to handle!

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Solving Trigonometric Equations
Cosine and Sine Functions

Formulas

cos(x) - sin(x) = √2 * cos(x + π/4)
cos(π/4) = 1/√2

Theorems

Trigonometric identities
Cosine of sum formula

Suitable Grade Level

Grades 11-12