问题
解答题
求值：
|
答案
=cos40°+sin50°(1+
tan10°)3 sin70° 1+sin50° cos40°+sin50°(1+
)
sin10°3 cos10° cos20° 1+cos40°
=
=
=cos40°+cos40°(
)2sin(10°+30°) cos10°
cos220°2
=cos40°+1
cos220°2
．2
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