2cosacosb Formula

As we know that there are six trigonometric functions of angles and their names are

  1. Sine
  2. Cosine
  3. Tangent
  4. Cotangent
  5. Secant
  6. Cosecant

These functions are in relation to the right triangle in the following ways:

In a right triangle ABC,

Sin A = Perpendicular/ Hypotenuse

Cos A = Base/ Hypotenuse

Tan A = Perpendicular/ Base

Sec A = Base/ Perpendicular

Cosec A = Hypotenuse/Perpendicular

Cot A = Hypotenuse/ Base

Formula of 2cosacosb

We know that,

cos (A+B) = cos A cos B – sin A sin B ….. (1)

cos (A-B) = cos A cos B + sin A sin B ….. (2)

Adding 1 and 2, we get

cos (A+B) + cos (A-B) = 2 cos A cos B.

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