sin²30°+根号2cos45°*cos60°-tan²45°...

sin²30°+根号2cos45°*cos60°-tan²45°...
sin²30°+根号2cos45°*cos60°-tan²45°
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sin²30°+根号2cos45°*cos60°-tan²45°...
sin30 = 1/2 sin45 =三分之二有两个sin60 =三分之二三sin90 = 1
tan30 =三tan45 = 1 tan60 =三分之二三个tan90意义
cos30 =三分之二三cos45 =三分之二有两个cos60 = 1/2 cos90 = 0