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IDENTITIES IN TRIGONOMETRY

A right angled triangle has a hypotenuse, base and the pependicular side. Let angle A be the angle between the base and the hypotenuse.

Then

Sin A = perpendicular / hypotenuse

Cos A = base / hypotenuse

Tan A = (Sin A) / (Cos A) = perpendicular / base

Cot A = 1 / Tan A = (Cos A) / (Sin A)

Sec A = 1 / Cos A

Cosec A = 1/ Sin A

Certain basic Trignometry identities applicable to any angle are:

Sin (-A) = - Sin A

Cos (-A) = Cos A

Tan (-A) = - Tan A

Sin²A + Cos²A = 1

1 + Tan²A = Sec²A

1 + Cot²A = Cosec²A