# Find the value of cos^{- 1} (cos 13π/6)

**Solution:**

Inverse trigonometric functions as a topic of learning are closely related to the basic trigonometric ratios.

The domain (θ value) and the range(answer) of the trigonometric ratio are changed to the range and domain of the inverse trigonometric function.

Inverse trigonometric functions are the inverse ratio of the basic trigonometric ratios.

Here the basic trigonometric function of Sin θ = y, can be changed to θ = sin^{-1} y

⇒ cos^{- 1} (cos 13π / 6)

= cos^{- 1} [cos (2π + π / 6)]

As we know that cos (2π + x) = cos x

On substituting in the above equation, we get

= cos^{- 1} [cos π / 6]

= π / 6

NCERT Solutions for Class 12 Maths - Chapter 2 Exercise ME Question 1

## Find the value of cos^{- 1} (cos 13π / 6)

**Summary:**

The value of cos^{- 1} (cos 13π / 6) is π / 6. Inverse trigonometric functions as a topic of learning are closely related to the basic trigonometric ratios

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