Question 60

$$(cosA+sinA)^{2} +(cosA-sinA)^{2}$$ is equals to

Solution

Expression : $$(cosA+sinA)^{2} +(cosA-sinA)^{2}$$

= $$(cos^2 A + sin^2 A + 2.sin A.cos A) + (cos^2 A + sin^2 A - 2.sin A.cos A)$$

= $$(1 + 2.sin A.cos A) + (1 - 2.sin A.cos A)$$

= $$1 + 1 = 2$$

=> Ans - (C)

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