Trigonometry Practice Test 1

Question : 18 of 40

Marks: +1, -0

If sin x - cos x = 0, then what is the value of

\sin^4 x + \cos^4 x

Solution:

\sin x - \cos x = 0

⇒\sin x = \cos x

⇒\tan x=1=\tan π/4

⇒x=π/4

\sin^4 x + \cos^4 x

=\sin^4 π/4+ \cos^4 π/4

=(1/√2)^4+(1/√2)^4=1/4+1/4=1/2

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