written 5.7 years ago by |
The given vector is V = ai + bj + ck
a=0, b=1, c=1
also |¯V|=√a2+b2+c2
Step 1: Rotation of vector V about X-axis by an angle θ=+θ1 {+ve indicates CCW}
Now, ,V1=bj+ck
Also,
1(V1)=√b2+c2
From figure, sinθ1=b/√b2+c2
cosθ1=c/√b2+c2
Let, √b2+c2=λ
So, sinθ1=b/λ and cosθ1=c/λ
Now, the rotational matrix about x-axis is,
[Rx]=[10000cosθsinθ00−sinθcosθ00001]
On substituting the values of sinθ1 and cosθ1, we get,
[Rx]=[10000cλbλ00−bλcλ00001]
Step 2: Rotate vector V1 about Y -axis by an angle of θ=−θ2 So as to consider with z-axis.
From fig, sinθ2=a/√a2+b2+c2=a/|V|
cosθ2=√b2+c2/√a2+b2+c2=λ/|V|
Now, rotational matrix about y-axis is,
[Ry]=[cosθ0−sin(−θ)00100sin(−θ)0cos(−θ)00001]
[Ry]=[λ|¯V|0−(−a|¯V|)00100−a|¯V|0λ|¯V|00001]
[Ry]=[λ|¯V|0a|¯V|00100−a|¯V|0λ|¯V|00001]
Now, combined transformation,
[Av] = [Rx][Ry]
[Rx]=[10000cλbλ00−bλcλ00001][λ|¯V|0a|¯V|00100−a|¯V|0λ|¯V|00001]
[Av]=[λ|¯V|0a|¯V|0−abλ|¯V|cλb|¯V|0−acλ|¯V|−bλc|¯V|00001]
This is the matrix [Av] which aligns a given vector v=ai+bj+ck with the vector k along positive z-axis