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  