(tan10°-根号3)*(sin80°/cos40°
来源:学生作业帮 编辑:作业帮 分类:数学作业 时间:2024/07/03 12:32:34
(tan10°-根号3)*(sin80°/cos40°
(tan10°-√3)*(sin80°/cos40°)
=(tan10°-√3)*(sin80°/cos40°)
=(sin80/cos40)(cot80-√3)
=(sin80/cos40)*(cos80/sin80)-(sin80/cos40)*√3
=cos80/cos40-√3sin80/cos40
=-(√3sin80-cos80)/cos40
=-2(√3/2*sin80-1/2*cos80)/cos40
=-2(sin80cos30-cos80sin30)/cos40
=-2sin(80-30)/cos40
=-2sin50/cos40
=-2sin(90-40)/cos40
=-2cos40/cos40
=-2
再问: 为什么可以用cot来算
再答: tan10° =tan(90°-80°) =cot80° 方便计算
再问: 那也是tan80°啊。。。。。还是不明白
再答: 公式六: π/2±α及3π/2±α与α的三角函数值之间的关系: sin(π/2+α)= cosα cos(π/2+α)= -sinα tan(π/2+α)= -cotα cot(π/2+α)= -tanα sin(π/2-α)= cosα cos(π/2-α)= sinα tan(π/2-α)= cotα cot(π/2-α)= tanα sin(3π/2+α)= -cosα cos(3π/2+α)= sinα tan(3π/2+α)= -cotα cot(3π/2+α)= -tanα sin(3π/2-α)= -cosα cos(3π/2-α)= -sinα tan(3π/2-α)= cotα cot(3π/2-α)= tanα
=(tan10°-√3)*(sin80°/cos40°)
=(sin80/cos40)(cot80-√3)
=(sin80/cos40)*(cos80/sin80)-(sin80/cos40)*√3
=cos80/cos40-√3sin80/cos40
=-(√3sin80-cos80)/cos40
=-2(√3/2*sin80-1/2*cos80)/cos40
=-2(sin80cos30-cos80sin30)/cos40
=-2sin(80-30)/cos40
=-2sin50/cos40
=-2sin(90-40)/cos40
=-2cos40/cos40
=-2
再问: 为什么可以用cot来算
再答: tan10° =tan(90°-80°) =cot80° 方便计算
再问: 那也是tan80°啊。。。。。还是不明白
再答: 公式六: π/2±α及3π/2±α与α的三角函数值之间的关系: sin(π/2+α)= cosα cos(π/2+α)= -sinα tan(π/2+α)= -cotα cot(π/2+α)= -tanα sin(π/2-α)= cosα cos(π/2-α)= sinα tan(π/2-α)= cotα cot(π/2-α)= tanα sin(3π/2+α)= -cosα cos(3π/2+α)= sinα tan(3π/2+α)= -cotα cot(3π/2+α)= -tanα sin(3π/2-α)= -cosα cos(3π/2-α)= -sinα tan(3π/2-α)= cotα cot(3π/2-α)= tanα
(1+根号3tan10°)·cos40°求值
cos40°(1+根号3tan10°)=?
2COS40°(1+根号3 *TAN10°)的值...
求值:cos40°(1+3tan10°)
化简:[sin50°+cos40°(1+根号3tan10°)]/sin²70°
求值{cos40°+sin50°(1+根号3tan10°)}/1+sin50°
人心齐泰山移Cos40°(1+根号3·tan10°)=?
cos40*[1+(根号3)tan10]
请问这个题怎么解?sin50°+sin10°(1+根号3*tan10°)根号下2*sin80°平方
化简【2sin50°+sin10°(1+根号3tan10°)】乘根号下2(sin80°的平方)
[cos40°+sin50°(1+√3tan10°)]/[sin70°√(1+cos40°)]=
(cos40°+sin50°(1+√3tan10°))/sin70°√(1+cos40°)