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求值：
cos40°+sin50°(1+
3
tan10°)
sin70°
1+sin50°
．
人气：475 ℃　时间：2020-04-27 15:39:34
解答
cos40°+sin50°(1+
3
tan10°)
sin70°
1+sin50°
=
cos40°+sin50°(1+
3
sin10°
cos10°
)
cos20°
1+cos40°

=
=
cos40°+cos40°(
2sin(10°+30°)
cos10°
)
2
cos220°
=
cos40°+1
2
cos220°
=
2
．
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