cos75度等于几分之几
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cos75度等于几分之几cos75度等于几分之几cos75度等于几分之几cos75=cos(45+30)=cos45cos30-sin45sin30=(√2/2)*(√3/2)-(√2/2)*(1/2
cos75度等于几分之几
cos75度等于几分之几
cos75度等于几分之几
cos75
=cos(45+30)
=cos45cos30 - sin45sin30
=(√2/2) * (√3/2) - (√2/2)* (1/2)
==(√6-√2)/4
cos(A+B)=cosAcosB - sinAsinB
cos75度=sin15度=（√6-√2）/4
（√6-√2）/4