sin13°cos17°-sin103°cos107°= cos70°sin40°-sin70°cos40°=
来源:学生作业帮 编辑:作业帮 分类:数学作业 时间:2024/05/23 11:29:13
sin13°cos17°-sin103°cos107°= cos70°sin40°-sin70°cos40°=
利用诱导公式和两角和的正弦余弦公式即可
(1)
sin13°cos17°-sin103°cos107°
=sin13°cos17°-sin(90°+13°)cos(90°+17°)
=sin13°cos17°-cos13°(-sin17°)
=sin13°cos17°+cos13°sin17°
=sin(13°+17°)
=sin30°
=1/2
(2)
cos70°sin40°-sin70°cos40°
= sin40°cos70°-cos40°sin70°
= sin(40°-70°)
= sin(-30°)
= -sin30°
= -1/2
(1)
sin13°cos17°-sin103°cos107°
=sin13°cos17°-sin(90°+13°)cos(90°+17°)
=sin13°cos17°-cos13°(-sin17°)
=sin13°cos17°+cos13°sin17°
=sin(13°+17°)
=sin30°
=1/2
(2)
cos70°sin40°-sin70°cos40°
= sin40°cos70°-cos40°sin70°
= sin(40°-70°)
= sin(-30°)
= -sin30°
= -1/2
sin70°-cos70°/sin70°+cos70°=多少啊
1,已知在三角形ABC中,a=1,b=4,c=60°,则c=?2,sin70°cos40°-cos70°sin40°=?
[cos40°+sin50°(1+√3tan10°)]/[sin70°√(1+cos40°)]=
[cos40°+sin50°(1+√3tan10°)]/[sin70°√(1+cos40°)]=?
利用和(差)角公式求下列各式的值:(1)sin13°cos17°+cos17°sin17°;cos80°cos20°+s
sin10°^2+cos40°^2+sin10°sin40°
计算sin50°cos40°+cos50°sin40°
sin40°cos10°-cos40°sin10°
计算:(sin20°-sin40°)÷(cos20°-cos40°)
sin50°*cos40°+cos50°*sin40°
化简 根号1-2sin40°cos40°
全部根号1-2sin40°cos40°