Product identities

The product relation of a trigonometric function with another trigonometric function is called product identity.

Introduction

Every trigonometric function has a special relation with another trigonometric function in product form. So, the six trigonometric ratios form three product trigonometric identities and they are used as formulas in trigonometry.

Sine and Cosecant functions

The product of sin and cosecant functions at an angle of a right triangle is equal to one.

$\sin{\theta}\csc{\theta} \,=\, 1$

Cosine and Secant functions

The product of cos and secant functions at an angle of a right triangle is equal to one.

$\cos{\theta}\sec{\theta} \,=\, 1$

Tangent and Cotangent functions

The product of tan and cot functions at an angle of a right triangle is equal to one.

$\tan{\theta}\cot{\theta} \,=\, 1$