sin50°(cos10°+√3sin10°)/sin80°的值()A1/2 B-1/2 C1 D-1

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sin50°(cos10°+√3sin10°)/sin80°的值()A1/2 B-1/2 C1 D-1
sin50°(cos10°+√3sin10°)/sin80°的值()
A1/2 B-1/2 C1 D-1

sin50°(cos10°+√3sin10°)/sin80°的值()A1/2 B-1/2 C1 D-1
C.
sin50°(cos10°+√3sin10°)/sin80°
= sin50° ( 2sin(10°+30°) )/sin80°
= 2cos40°sin40°/sin80°
= sin80°/sin80°= 1