Trigonometric Identities

Pythagoren Identities

1. sin²x + cos²x = 1
   
   
2. tan²x + 1 = sec²x
   
   
3. 1 + cot²x = csc²x

Reciprocal Identities

1. csc x = 1 / sin x
   
   
2. sec x = 1 / cos x
   
   
3. cot x = 1 / tan x

The Tangent and Cotangent Identities

1. tan x = sin x / cos x
   
   
2. cot x = cos x / sin x

Identities for Negatives

1. sin (-x) = - sin x (the sine function is an odd function)
   
   
2. cos (-x) = cos x (the cosine function is an even function)
   
   
3. tan (-x) = - tan x (the tangent function is an odd function)