# The Unit Circle, Basic Introduction, Trigonometry | Summary and Q&A

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October 12, 2017
by
The Organic Chemistry Tutor
The Unit Circle, Basic Introduction, Trigonometry

## TL;DR

The unit circle is a circle with a radius of one, and it helps in evaluating trigonometric functions such as sine and cosine.

## Key Insights

• 👨‍💼 The unit circle is a valuable tool in trigonometry as it helps in evaluating sine and cosine functions.
• ❣️ The x coordinate represents the cosine value, while the y coordinate represents the sine value on the unit circle.
• 🔺 Understanding the values in quadrant one is sufficient in finding the values for angles in other quadrants.
• ⭕ The symmetry of the unit circle allows for easily determining the values for angles not directly shown on the circle.
• 🤩 The key angles to remember on the unit circle include 30, 45, and 60 degrees.
• ❣️ The values of sine and cosine depend on the x and y coordinates respectively.
• ❣️ Angles with the same reference angle on the unit circle have similar x and y values, just with a different sign.

## Transcript

now let's talk about the unit circle so what exactly is the unit circle the unit circle is a circle with a radius of one so if we draw a ray at a 45 degree angle and let's say if we turn it into a triangle the hypotenuse of that triangle will be equal to 1. at a 45 degree angle the x and y portion of the triangle have the same value so therefore th... Read More

### Q: What is the unit circle and why is it important in trigonometry?

The unit circle is a circle with a radius of one and is important in trigonometry because it helps in evaluating trigonometric functions based on the x and y values of points on the circle.

### Q: How do you determine the value of sine and cosine using the unit circle?

To determine the value of sine, you look at the y coordinate of a point on the unit circle, while for cosine, you look at the x coordinate.

### Q: Why do some values on the unit circle repeat in different quadrants?

Some values on the unit circle repeat in different quadrants because of the symmetry of the circle. The x and y values change sign depending on the quadrant.

### Q: How can you find the values of trigonometric functions for angles not shown on the unit circle?

By knowing the values in the first quadrant and understanding the symmetry of the unit circle, you can determine the values for angles in other quadrants without memorizing the entire unit circle.

## Summary & Key Takeaways

• The unit circle is a circle with a radius of one and is used to evaluate sine and cosine functions based on the x and y values of points on the circle.

• The values of sine and cosine can be determined by looking at the y and x coordinates respectively on the unit circle.

• Common values on the unit circle include 30, 45, and 60 degrees, which have specific x and y values.