Q2 of 268 Page 4

Express the following as trigonometric ratio of complementary angle of 90o- θ.

(i) tan (90o- θ)


(ii) cos (90o- θ)

(i) We know that,




[∵ sin 90° = 1 and cos 90° = 0]



⇒ tan (90° - θ ) = cot θ


(ii) We know that.


Cos(A - B) = cos A cos B + sin A sin B


⇒ cos (90o- θ) = cos 90° cos θ + sin 90° sin θ


⇒ cos (90o- θ) = (0) cos θ + (1) sin θ


⇒ cos (90o- θ) = sin θ


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(i) sin A =…. (ii) cos B =…


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