# Solve the Trigonometric Equation cos^2(x) - sin^2(x) = 1 | Summary and Q&A

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November 1, 2020
by
The Math Sorcerer
Solve the Trigonometric Equation cos^2(x) - sin^2(x) = 1

## TL;DR

The video discusses solving a trigonometric equation by using a trig identity and the unit circle.

## Key Insights

• ⭕ Trigonometric equations can be solved by using trig identities and the unit circle.
• ❎ The equation cosine squared minus sine squared can be simplified to cosine of 2x.
• 🟰 Using the unit circle, the angles where the cosine is equal to 1 can be identified.

## Transcript

in this problem we have a trigonometric equation we have cosine squared minus sine squared and that's actually equal to one so let's go ahead and try to work through this solution so it would be really nice if the right hand side was a 0 because we know that the left hand side is the difference of squares so you can write this as cosine x minus sin... Read More

### Q: How does the video suggest solving a trigonometric equation with cosine squared and sine squared?

The video suggests using the trig identity cosine squared minus sine squared equals cosine of 2x. This simplifies the equation and allows for further analysis.

### Q: Why does the video use the unit circle to solve for the values of x?

The unit circle is used because it relates the cosine and sine values to points on a circle. By identifying where the x coordinate is equal to 1, the angles that satisfy the equation can be found.

### Q: What are the solutions to the trigonometric equation?

The solutions to the equation are x = 0 and x = pi. These values satisfy the equation and are the only angles between 0 and 4pi where the cosine is equal to 1.

### Q: Can this method be used for other trigonometric equations?

Yes, this method can be applied to other equations with trig identities and the unit circle. By understanding the relationship between trigonometric functions and the unit circle, similar solutions can be obtained.

## Summary & Key Takeaways

• The video explains how to solve a trigonometric equation by finding the values of x that satisfy the equation.

• It demonstrates using a trig identity to simplify the equation and then using the unit circle to identify the angles where the cosine is equal to 1.

• The final answer is x = 0 and x = pi.