NCERT - Mathematics

Book: NCERT - Mathematics

Chapter: 8. Introduction to Trigonometry

Subject: Maths - Class 10th

Q. No. 7 of Exercise 8.1

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7

If evaluate:

(i)


(ii)

Let us consider a right triangle ABC, right-angled at point B


Cot =


= If BC is 7k, then AB will be 8k, where k is a positive integer.


Applying Pythagoras theorem in ΔABC, we obtain


AC2 = AB2 + BC2


= (8k)2 + (7k)2


= 64k2 + 49k2


= 113k2


AC = k


Sin =


=


=


Cos θ =


=


=


(i) = (1 – sin2 θ)/(1 – cos2 θ)


=


=


=


(ii) Cot2 θ = (cot θ)2


= (2 =


13

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