(cos80°-cos20°)/sin80°+sin20°)=
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(cos80°-cos20°)/sin80°+sin20°)=
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cos20°+cos100°+cos140°=
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cos20°+cos100°+cos140°=
(cos80°-cos20°)/(sin80°+sin20°)
=[cos(50°+30°)-cos(50°-30°)]/[sin(50°+30°)+sin(50°-30°)]
=[(cos50°cos30°-sin50°sin30°)- (cos50°cos30°+sin50°sin30°)]/[ (sin50°cos30°+cos50°sin30°)+ (sin50°cos30°-cos50°sin30°)]
=(-2sin50°sin30°)/ (2sin50°cos30°)
= -2sin30°/ cos30°
= -tan30°
= -√3/3
cos20°+cos100°+cos140°
= cos (80°-60°)+cos100°+cos(80°+60°)
= (cos80°cos60°+sin80°sin60°)+cos100°+ (cos80°cos60°-sin80°sin60°)
= 2cos80°cos60°+cos100°
= cos80°+cos100°
= cos80°-cos80°
=0
=[cos(50°+30°)-cos(50°-30°)]/[sin(50°+30°)+sin(50°-30°)]
=[(cos50°cos30°-sin50°sin30°)- (cos50°cos30°+sin50°sin30°)]/[ (sin50°cos30°+cos50°sin30°)+ (sin50°cos30°-cos50°sin30°)]
=(-2sin50°sin30°)/ (2sin50°cos30°)
= -2sin30°/ cos30°
= -tan30°
= -√3/3
cos20°+cos100°+cos140°
= cos (80°-60°)+cos100°+cos(80°+60°)
= (cos80°cos60°+sin80°sin60°)+cos100°+ (cos80°cos60°-sin80°sin60°)
= 2cos80°cos60°+cos100°
= cos80°+cos100°
= cos80°-cos80°
=0
在平面直角坐标系中,已知两点A(cos80°,sin80°)、B(cos20°,sin20°),则AB两点的距离为
1.(1—cos20° )除以(cos80° 乘sin20° )=根号二
求值:cos20°sin20°
计算cos20°cos40°cos80°
请帮忙计算:不可以用计算器哦,只能化简求值:sin20°^2+cos80°^2+根号3*cos20°*cos80°知道的
计算cos20°cos40°cos80°=多少
1/cos20°-根号3/sin20°
求值:(2sin80°-cos70°)/cos20°
cos20°cos40°cos80°怎么算
1.cos20°cos40°cos80°的值为?
求cos20°cos40°cos80°的值
化简:sin50º(1+√3tan10°)-cos20°/cos80°√(1-cos20°)