10/12/22 - Unit Circle and Angles Flashcards
1
Q
What is a unit circle?
A
A circle with a radius of 1 centered at the origin.
2
Q
When an angle is positive, how do you draw it on the unit circle?
A
Start at the positive x-axis and go counterclockwise.
3
Q
When an angle is negative, how do you draw it on the unit circle?
A
Start at the positive x-axis and go clockwise.
4
Q
Clockwise = negative, counterclockwise = _____
A
Positive
5
Q
How do you define an angle in a unit circle?
A
The amount of counterclockwise rotation needed to move the positive x-axis to the terminal leg of an angle.
6
Q
If a point (x, y) is on the unit circle, then it satisfies x^2 + y^2 = 1.
Why?
A
Because the radius of the unit circle is 1. This is derived from the Pythagorean Theorem.
7
Q
Is (1, 2) on the unit circle?
A
No, because it does not satisfy x^2 + y^2 = 1
