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Glossary
Look up any term from this course. Each entry links back to the lesson that taught it.
| Term | Definition | Lesson |
|---|---|---|
| Acute angle | An angle between ° and °. | Angles and Triangles |
| Adjacent side | The side next to the angle being used, that is not the hypotenuse. | The Three Ratios |
| Amplitude | The maximum distance a wave graph rises or falls from its middle value. | Graphs of Sine and Cosine |
| Angle of depression | The angle measured downward from the horizontal to a point below the observer. | Angles of Elevation and Depression |
| Angle of elevation | The angle measured upward from the horizontal to a point above the observer. | Angles of Elevation and Depression |
| ASTC rule | "All Students Take Calculus" — which trig ratio is positive in each quadrant. | Trig Ratios of Any Angle |
| Asymptote | A line that a graph approaches but never touches. | The Graph of Tangent |
| Hypotenuse | The longest side of a right-angled triangle, opposite the right angle. | Angles and Triangles |
| Inverse sine, cosine, tangent | sin⁻¹, cos⁻¹, tan⁻¹ — reverse a ratio back into an angle. | Finding Missing Angles |
| Obtuse angle | An angle between ° and °. | Angles and Triangles |
| Opposite side | The side directly across from the angle being used. | The Three Ratios |
| Period | The horizontal distance after which a repeating graph pattern starts again. | Graphs of Sine and Cosine |
| Pythagoras' theorem | For a right-angled triangle: , where c is the hypotenuse. | Pythagoras' Theorem |
| Pythagorean identity | sin²(θ) + cos²(θ) = , true for every angle θ. | The Pythagorean Identity |
| SOH CAH TOA | sin = Opposite ÷ Hypotenuse, cos = Adjacent ÷ Hypotenuse, tan = Opposite ÷ Adjacent. | The Three Ratios |
| Unit circle | A circle of radius used to define sin(θ) and cos(θ) for any angle. | The Unit Circle |
More lessons in Trigonometry · Previous: Course Exam