若 cos2a/sin(a-π/4)= -√2/2,求cosa+sina的值.
来源:学生作业帮 编辑:作业帮 分类:数学作业 时间:2024/03/29 20:40:55
若 cos2a/sin(a-π/4)= -√2/2,求cosa+sina的值.
cos2a/sin(a-π/4)= -√2/2,
sin(π/2-2a) /sin(a-π/4)= -√2/2,
-sin(2a-π/2) /sin(a-π/4)= -√2/2,
[-2 sin(a-π/4)cos(a-π/4)) /sin(a-π/4)= -√2/2,
-2 cos(a-π/4))= -√2/2,
-2[cos a cosπ/4+sin a sinπ/4] = -√2/2,
-√2(cosa+sina) = -√2/2,
所以cosa+sina=1/2.
sin(π/2-2a) /sin(a-π/4)= -√2/2,
-sin(2a-π/2) /sin(a-π/4)= -√2/2,
[-2 sin(a-π/4)cos(a-π/4)) /sin(a-π/4)= -√2/2,
-2 cos(a-π/4))= -√2/2,
-2[cos a cosπ/4+sin a sinπ/4] = -√2/2,
-√2(cosa+sina) = -√2/2,
所以cosa+sina=1/2.
若 cos2a/sin(a-π/4)= -√2/2,求cosa+sina的值.
若cos2a/sin((a-(π/4))=-(√2)/2,则cosa+sina的值为
cos2a/sin(a-π/4) =-根号(2)/2,则cosa+sina的值为?
若cos2a/sin(a-π/4)=-√2/2,则cosa+sina等于多少?
若cos2a/sin(a-π/4)=-根号2/2 则sina+cosa 的值为多少?
若cos2a/sin(a-45°)=-根号2/2,则cosa+sina的值为?
若sin(a-π/4)/cos2a=-根号2,则sina+cosa=
高一三角函数习题若cos2a/sin(a-π/4)=-√2/2,则cosa+sina的值为 ( )A.-√7/2 B.-
已知a∈(0,π/2),且cos2a=4/5,求sina+cosa的值
cos2a/sin(a-pai/4)=-根号2/2求cosa+sina
已知(2sina+cosa)/(sina-3cosa)=-5,求3cos2a+4sin2a的值
已知2sina+cosa/sina-3cosa=-5,求3cos2a+4sin2a的值