a.b
=(cos(3x/2),sin(3x/2)).(cos(x/2),-sin(x/2))
=cos(3x/2).cos(x/2)- sin(3x/2).sin(x/2)
=cos2x
|a+b|^2
=(cos(3x/2)+cos(x/2))^2+ (sin(3x/2)-sin(x/2))^2
= 2 + 2(cos(3x/2)cos(x/2)- sin(3x/2)sin(x/2) )
=2 + 2cos2x
|a+b| =√(2 + 2cos2x)
已知向量a=(cos3/2x,sin3/2x),b=(cos1/2x,-sin1/2x),x属于【-π/8,π/4】 求
1个回答
相关问题
-
已知向量a=（cos3/2x,sin3/2x),b=(cos1/2x,sin1/2x),x属于[0,π/2] 求f(x)
-
已知向量a=(cos(2x-π/3),sin(x-π/4)),向量b=(1,2sin(x π/4)),函数f(x)=向量
-
已知向量a=(cos 3x/2,sin3x/2),b=(cos x/2,-sin x/2),且x∈{-π/2,π/2]
-
已知向量a=(cos2/3x,sin2/3x),b=(cos2/x,-sin2/x),且x属于[0,π/2]
-
已知向量a=(cos(3x/2),sin(3x/2)),向量b=(cos(x/2),-sin(x/2)),其中x∈[-π
-
求函数y=[sin2x+sin(2x+π/3)-cos1/2﹙π-4x﹚]/[cos2x+cos﹙2x+π/3﹚-sin
-
已知向量a=[cos(3x/2),sin(3x/2)],向量b=[cos(x/2),-sin(x/2)],且x[0,π/
-
已知cos(1/x)-sin(1/x)=1,x属于（π,2π）,求sin2x
-
已知f(x)＝sin(x−3π)•cos(2π−x)•sin(−x+3π2)cos(−x−π)•cos(π2−x)
-
已知(1+tanx)/(1-tanx)=2 求cos^2(π+x)+3sin(π-x)cos(-x)+2sin^2(2π