sinA+sinB+sinc=0 cosA+cosB+cosC=0 cos(B-C)
来源:学生作业帮 编辑:搜搜做题作业网作业帮 分类:数学作业 时间:2024/08/12 01:21:41
sinA+sinB+sinc=0 cosA+cosB+cosC=0 cos(B-C)
![sinA+sinB+sinc=0 cosA+cosB+cosC=0 cos(B-C)](/uploads/image/z/3302878-22-8.jpg?t=sinA%2BsinB%2Bsinc%3D0+cosA%2BcosB%2BcosC%3D0+cos%28B-C%29)
cos(B-C)=cosBcosC+sinBsinc又sinB+sinc=-sinA cosB+cosC=-cosA
所以同时平方sinB^2+sinc^2+2sinBsinc=sinA^2 cosB^2+cosc^2+2cosBcosC=cosA^2 两式相加 2(cosBcosC+sinBsinc)+2=1
cos(B-C)=cosBcosC+sinBsinc=-1/2
所以同时平方sinB^2+sinc^2+2sinBsinc=sinA^2 cosB^2+cosc^2+2cosBcosC=cosA^2 两式相加 2(cosBcosC+sinBsinc)+2=1
cos(B-C)=cosBcosC+sinBsinc=-1/2
sinA+sinB+sinc=0 cosA+cosB+cosC=0 cos(B-C)
sinA+sinB+sinC=0; cosA+cosB+cosC=0,求cos(B-C)的值?
sina+sinb+sinc=0,cosa+cosb+cosc=0,求cos(B-C)的值?
sinA+sinB+sinC=0,cosA+cosB+cosC=o,则cos(A-B)=______
(1)已知sinA+sinB+sinC=0,cosA+cosB+cosC=0.求cos(B-C)的值.
sina+sinb+sinc=0 cosa+cosb+cosc=0求证cos*2a+cos*2b+cos*2c=3|2
cosa+cosb+cosc=sina+sinb+sinc=0 求(cosa)^2+(cosb)^2+(cosc)^2
sinA+sinB+sinC>=cosA+cosB+cosC
已知sina+sinb+sinc=0,cosa+cosb+cosc=0,则cos(a-b)的值是?
已知sinA+sinB+sinC=0,cosA+cosB+cosC=0,求cos(A-B)的值
已知sina+sinb+sinc=0且cosa+cosb+cosc=0 求cos(a-b)的值
设A,B,C属于(0,90度),SINA+SINC=SINB,COSB+COSC=COSA,则B-A等于