# TRIGONOMETRY - Cofunction Identities

Cofunction Identities in Trigonometry :

## Solved Problems

Problem 1 :

Solution :

Problem 2 :

Solution :

Problem 3 :

Solution :

cos θ is an even trigonometric ratio. So, we have

cos (-θ) = cos θ

Problem 4 :

Solution :

tan θ is an odd trigonometric ratio. So, we have

tan (-θ) = -tan θ

tan (-θ) = -1.48

-tan θ = -1.48

tan θ = 1.48

Problem 5 :

Solution :

Problem 6 :

Solution :

Problem 7 :

Solution :

Problem 8 :

Solution :

sin θ is an odd trigonometric ratio. So, we have

sin (-θ) = -sin θ

Problem 9 :

Solution :

Problem 10 :

Solution :

sec θ is an even trigonometric ratio. So, we have

Problem 11 :

If cos 60° = 0.5, find the value of sin 30°.

Solution :

sin 30° = cos (90° - 30°)

= cos 60°

= 0.5

Problem 12 :

If tan 45° = 1, find the value of cot 45°.

Solution :

cot 45° = tan (90° - 45°)

= tan 45°

= 1

Problem 13 :

If cot 30° = √3, find the value of tan 60°.

Solution :

tan 60° = cot (90° - 60°)

= cot 30°

= √3

Solution :

sec θ is an even trigonometric ratio. So, we have

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