已知sina+sin^2a=1,求3cos^2a+ - 知识问答

已知sina+sin^2a=1,求3cos^2a+cos^4a-2sina+1

1个回答

sina+sin²a=1
∴sina=1-sin²a=cos²a
3cos^2a+cos^4a-2sina+1
=3sina+sin²a-2sina+1
=sina+1-cos²a+1
=sina+1-sina+1
=2

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