# Right Triangle Trigonometry

### Trigonometric Identities

H is the *Hypotenuse*, always being opposite the right angle. Relative to angle x, O is the *Opposite* and A is the *Adjacent*.

"Arc" functions such as "arcsin", "arccos", and "arctan" are the complements of normal trigonometric functions. These functions return an angle for a ratio input. For example, if the tangent of 45^{o} is equal to 1, then the "arctangent" (arctan) of 1 is 45^{o}. "Arc" functions are useful for finding angles in a right triangle if the side lengths are known.

### The Pythagorean Theorem

**Lessons In Electric Circuits** copyright (C) 2000-2020 Tony R. Kuphaldt, under the terms and conditions of the *CC BY License**.*

**Lessons In Electric Circuits**

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Revised July 25, 2007

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