sinA +cosA= 3 then sin⁴A+cos⁴A=?
a)0
b)32
c)-31
d)1
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0
I think the answer is 32
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( sinA + cosA )(sinA + cosA ) = 9
sin^2A + cos^2A + 2sinAcosA = 9
sinAcosA = 4
sin^4A + cos^4A + 2sin^2Acos^2A - 2 sin^2Acos^2A
( sin^2A + cos ^2A )^2 - 2sin^2Acos^2A
1 - 2×16 = -31
sin^2A + cos^2A + 2sinAcosA = 9
sinAcosA = 4
sin^4A + cos^4A + 2sin^2Acos^2A - 2 sin^2Acos^2A
( sin^2A + cos ^2A )^2 - 2sin^2Acos^2A
1 - 2×16 = -31
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