问题
填空题
求值：cos40°(1+
|
答案
cos40°(1+
tan10°)=sin50°(1+3
tan10°)=3
=sin50°(cos10°+
sin10°)3 cos10°
=2sin50°sin(30°+10°) cos10°
=2cos40° sin40° cos10°
=1sin80° cos10°
故答案为：1．
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求值：cos40°(1+
|
cos40°(1+
tan10°)=sin50°(1+3
tan10°)=3
=sin50°(cos10°+
sin10°)3 cos10°
=2sin50°sin(30°+10°) cos10°
=2cos40° sin40° cos10°
=1sin80° cos10°
故答案为：1．