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Question -

sin6 x + cos6 x= 1 – 3 sin2 x cos2 x



Answer -

Let us consider LHS: sin6 x+ cos6 x

(sin2 x) 3 +(cos2 x) 3

By using the formula, a3 + b3 =(a + b) (a2 + b2 – ab)

(sin2 x + cos2 x)[(sin2 x) 2 +(cos2 x) 2 –sin2 x cos2 x]

By using the formula, sin2 x + cos2 x= 1 and a2 + b2 = (a + b) 2 –2ab

1 × [(sin2 x + cos2 x) 2 – 2sin2 xcos2 x – sin2 x cos2 x

12 –3sin2 x cos2 x

1 – 3sin2 x cos2 x

= RHS

∴LHS = RHS

Hence proved.

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