- Trigonometry
- Angles in Standard Positions
- Coterminal Angles
- Angle Conversion
- Origins of Trigonometry
- Trigonometric Ratios
- Solving a Right-Angle Trigonometry Question
- Pythagorean Theorem
- Inverse Trigonometric Functions
- Trigonometric Circle
- Sine and Cosine Law
- Simplifying Trigonometric Expressions
- Graphing Trigonometric Functions
- Proving Trigonometric Identities

In this section we’ll only consider sines of angles between 0° and 90°. In the section on trigonometric functions, we’ll define sines for arbitrary angles.

A sine (*CE*)* *is half of a chord (*CD*). More accurately, the sine of an angle (*CAB*) is half the chord of twice the angle (*CAD*). Inside the circle segment, a right angle triangle *ACE* is formed.

In a unit circle, where the radius is of length 1. Sine (or sin) represents the opposite side of angle *CAE*. Cosine (or cos) represents what is called the adjacent side *AE *to angle *CAE*.

When you generalize the radius to any length, the lengths change in proportion resulting in the trigonometric ratios. The radius is referred to as the hypotenuse. These proportions form the primary trigonometric ratios.

Keep in mind the right angle triangle can be oriented in different ways. However, the sides are still in relation to the angle.

Designed by Matthew Cheung. This work is licensed under a Creative Commons Attribution 4.0 International License.

- Last Updated: Apr 11, 2023 5:52 PM
- URL: https://libraryguides.centennialcollege.ca/c.php?g=716824
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