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问题: 高中三角函数

(3-sin10)/(2-cos10*cos10)

解答:

有没有抄错?改一下题目吧,否则无法做啊!
(3-sin10°)/(2-cos40°*cos40°)
=(3-sin10°)/[2-(1+cos80°)/2]
=2*(3-sin10°)/(3-cos80°)
=2*(3-sin10°)/(3-sin10°)
=2.

或者
(3-sin70°)/(2-cos10°*cos10°)
=(3-sin70°)/[2-(1+cos20°)/2]
=2*(3-sin70°)/(3-cos20°)
=2*(3-sin70°)/(3-sin70°)
=2.