tan(-2010°)+cos(-79π/6)
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tan(-2010°)+cos(-79π/6)
tan(-2010°)+cos(-79π/6)
tan(-2010°)+cos(-79π/6)
【1】
tan(-2010º)=-tan2010º=-tan[6×360º-150]=tan150º=tan(180º-30º)=-tan30º=-(√3)/3
【2】
cos(-79π/6)=cos(79π/6)=cos[12π+(7π/6)]=cos(7π/6)=cos[π+(π/6)]=-cos(π/6)=-(√3)/2
【3】
原式=-(√3)[(1/3)+(1/2)]=-(√3)×(5/6)=-(5√3)/6
tan(-2010°)+cos(-79π/6)
=-tan30°+(-cosπ/6)
=-√3/3-√3/2
=-5√3/6
原式=-tan2010°+cos(79π/6)
=-tan(1800°+210°)+cos[12π+(7π/6)]
=-tan210°+cos(7π/6)
=-tan(180°+30°)+cos(π+π/6)
=-tan30°-cos(π/6)
=-√3/3-√3/2
=-(5√3)/6
tan(-2010°)+cos(-79π/6)
=tan(-6x360°+150°)+cos(-6x2π-7π/6)
=-√3/3-√3/2=-5√3/6
tan(-2010°)+cos(-79π/6)
=tan(1980-2010)°+cos(14π-79π/6)
=-tan30°-cos30°
=-√3/3-√3/2
=-5√3/6
-2010°=-1080°-30°,所以tan(-2010°)=-tan30°=-根3/3
-79π/6=-13π-π/6,所以cos(-79π/6)=cosπ/6=根3/2
所以原式=根3/6
急看不清!!