在△ABC中,角A,B,C所对的对边长分别为a,b,c. (1)设向量x=(sinB,sinC),向量y=(cosB,cosC),向量z=(cosB,-c在△ABC中,角A,B,C所对的对边长分别为a,b,c.(1)设向量x=(sinB,sinC),向量y=(cosB,cosC),向量z=(cosB,-cosC),若z
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![在△ABC中,角A,B,C所对的对边长分别为a,b,c. (1)设向量x=(sinB,sinC),向量y=(cosB,cosC),向量z=(cosB,-c在△ABC中,角A,B,C所对的对边长分别为a,b,c.(1)设向量x=(sinB,sinC),向量y=(cosB,cosC),向量z=(cosB,-cosC),若z](/uploads/image/z/987321-57-1.jpg?t=%E5%9C%A8%E2%96%B3ABC%E4%B8%AD%2C%E8%A7%92A%2CB%2CC%E6%89%80%E5%AF%B9%E7%9A%84%E5%AF%B9%E8%BE%B9%E9%95%BF%E5%88%86%E5%88%AB%E4%B8%BAa%2Cb%2Cc.+%EF%BC%881%EF%BC%89%E8%AE%BE%E5%90%91%E9%87%8Fx%3D%28sinB%2CsinC%29%2C%E5%90%91%E9%87%8Fy%3D%28cosB%2CcosC%29%2C%E5%90%91%E9%87%8Fz%3D%28cosB%2C-c%E5%9C%A8%E2%96%B3ABC%E4%B8%AD%2C%E8%A7%92A%2CB%2CC%E6%89%80%E5%AF%B9%E7%9A%84%E5%AF%B9%E8%BE%B9%E9%95%BF%E5%88%86%E5%88%AB%E4%B8%BAa%2Cb%2Cc.%EF%BC%881%EF%BC%89%E8%AE%BE%E5%90%91%E9%87%8Fx%3D%28sinB%2CsinC%29%2C%E5%90%91%E9%87%8Fy%3D%28cosB%2CcosC%29%2C%E5%90%91%E9%87%8Fz%3D%28cosB%2C-cosC%29%2C%E8%8B%A5z)
在△ABC中,角A,B,C所对的对边长分别为a,b,c. (1)设向量x=(sinB,sinC),向量y=(cosB,cosC),向量z=(cosB,-c在△ABC中,角A,B,C所对的对边长分别为a,b,c.(1)设向量x=(sinB,sinC),向量y=(cosB,cosC),向量z=(cosB,-cosC),若z
在△ABC中,角A,B,C所对的对边长分别为a,b,c. (1)设向量x=(sinB,sinC),向量y=(cosB,cosC),向量z=(cosB,-c
在△ABC中,角A,B,C所对的对边长分别为a,b,c.
(1)设向量x=(sinB,sinC),向量y=(cosB,cosC),向量z=(cosB,-cosC),若z‖(x+y),求tanB+tanc的值
(2)已知a²-c²=8b,且sinAcosC+3cosAsinC=0,求b
在△ABC中,角A,B,C所对的对边长分别为a,b,c. (1)设向量x=(sinB,sinC),向量y=(cosB,cosC),向量z=(cosB,-c在△ABC中,角A,B,C所对的对边长分别为a,b,c.(1)设向量x=(sinB,sinC),向量y=(cosB,cosC),向量z=(cosB,-cosC),若z
1,x+y=(sinB+cosB,sinC+cosC)
z||(x+y),(sinB+cosB)/cosB=-(sinC+cosC)/cosC
tanB+1=-tanC-1 tanB+tanC=-2
2,sinAcosC+3cosAsinC=sin(A+C)+2cosAsinC
=sinB+2cosAsinC
=b+(b^2+c^2-a^2)/2bc*c*2=0
b=4