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九九乘法表查看:42 回复:7 评论:42 创建时间:2021-07-04T08:21:27
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(sin(23))^2-(sin(9))^2+(cos(23))^2-(cos(9))^2=?
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九九乘法表(sin(23))^2-(sin(9))^2+(cos(23))^2-(cos(9))^2
={[sin(23)]^2+[cos(23)]^2}-{[sin(9)]^2+[cos(9)]^2}
=1-1
=0
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