原式=2sin^2（3/4π)+tan^2(5/4π)*cot(-1/4π)
=2sin^2（3/4π)+tan^2(5/4π)*cot(-1/4π)
=2*（1/2）+tan^2(1/4π)*cot(-1/4π)
=1+1*(-1)
=1-1
=0
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