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Mathematics
Mathematics
Problem
Prove that
sin
4
θ
+
cos
4
θ
=
1
−
1
2
sin
2
2
θ
.
\sin^4\theta+\cos^4\theta=1-\tfrac12\sin^22\theta.
sin
4
θ
+
cos
4
θ
=
1
−
2
1
sin
2
2
θ
.
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