The value of (sinA + cosecA)2 + (cosA + secA)2 is :
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Correct answer: B
Explanation
The correct answer is option 2 i.e. 7 + tan2A + cot2A
(sin A + cosec A)2 + (cos A + sec A)2
= (sin2A + 2sinA cosecA + cosec2A) + (cos2A + 2cosA secA + sec2A)
= (sin2A + 2sinA(1/sinA) + cosec2A) + (cos2A + 2cosA(1/cosA) + sec2A)
= (sin2A + 2 + cosec2A) + (cos2A + 2 + sec2A)
= (sin2A + cos2A) + 2 + 2 + cosec2A + sec2A
= 1 + 4 + cosec2A + sec2A [∵ sin2A + cos2A = 1]
= 5 + cosec2A + sec2A
= 5 + (1 + cot2A) + (1 + tan2A) [∵ sec2A = 1 + tan2A and cosec2A = 1 + cot2A]
= 5 + 1 + cot2A + 1 + tan2A
= 7 + tan2A + cot2A
Therefore, the required value is 7 + tan2A + cot2A.