The ebook FEEE - Fundamentals of Electrical Engineering and Electronics is based on material originally written by T.R. Kuphaldt and various co-authors. For more information please read the copyright pages.

# Trigonometry Reference

TRIGONOMETRY REFERENCE

A right triangle is defined as having one angle precisely equal to 90o (a right angle).

### Trigonometric identities

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 45o is equal to 1, then the "arctangent" (arctan) of 1 is 45o. "Arc" functions are useful for finding angles in a right triangle if the side lengths are known.

### The Pythagorean theorem

Pythagorean Theorem

### The Law of Sines (for any triangle)

Law of sines Sines, law of

### The Law of Cosines (for any triangle)

Law of cosines Cosines, law of

Trigonometric equivalencies