Question

(1+cos a)(1-cos a)(1+cot^2a)=1
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Answer 1

Step-by-step explanation:

apply identity a²- b²= ( a+b) ( a-b)

i.e, (1+cos a) (1-cos a)= 1² - cos²a

thus becomes sin² a

1+ cot²a becomes cosec²a

thus sin²a ×cosec²a= 1

hence proved