(2cos10-sin20)/sin70的值是多少?.10.20和70都是度数

原式= (2cos10°-sin20°)/sin70°
=[2cos(30°-20°)-sin20°]/cos20°
=[√3cos20°]/cos20°
==√3.

原式= (2cos10°-sin20°)/sin70°
=(2cos10°-sin20°)/cos20°
=[cos10°+(cos10°-cos70°)]/cos20°
=[cos10°+2sin40°*sin30°]/cos20°
=[cos10°+2*1/2*sin40°]/cos20°
=[cos10°+cos50°]/cos20 °
=2cos30°*cos20°/cos20°
=2cos30°
= 根号3
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2cos10-sin20=2cos(30-20)-sin20=根号3cos20
所以结果为根号3