The Definitions of Sine and Cosine - Concept

Concept Concept (1)

The right triangle definitions of sine and cosine only apply to acute angles, so a more complete definition is needed. The point where the terminal side intersects the unit circle (x, y) is the basis for this definition. Since the radius (and therefore hypotenuse of the right triangle) is 1, the denominators cosine=adjacent/hypotenuse and sine=opposite/hypotenuse are also 1. Thus, the sine definition is y=sine and x=cosine.

Sample Sample Problems (4)

Need help with "The Definitions of Sine and Cosine" problems? Watch expert teachers solve similar problems to develop your skills.

The Definitions of Sine and Cosine - Problem 1
Problem 1
How to evaluate sine and cosine when the angle is 0, pi/2, pi, 3*pi/2.
The Definitions of Sine and Cosine - Problem 2
Problem 2
How to find the sine of an angle when its cosine is given.
The Definitions of Sine and Cosine - Problem 3
Problem 3
How to determine whether sine and cosine are positive or negative when we know the quadrant.
The Definitions of Sine and Cosine - Problem 4
Problem 4
How to determine the magnitude of sine or cosine using a unit circle diagram.