Loading [MathJax]/jax/output/SVG/jax.js
 
+0  
 
0
1089
4
avatar

(-1,-1,3) x (-1,0,2)

 Mar 22, 2015

Best Answer 

 #1
avatar+118702 
+10

(-1,-1,3) x (-1,0,2)

 

\\\begin{pmatrix}  -1&-1&3 \\  \end{pmatrix}   &\times \begin{pmatrix}  -1& \\   0&\\  2&   \end{pmatrix} \\\\  =(-1*-1)+(-1*0)+(3*2))\\=1+0+6\\=7

 Mar 22, 2015
 #1
avatar+118702 
+10
Best Answer

(-1,-1,3) x (-1,0,2)

 

\\\begin{pmatrix}  -1&-1&3 \\  \end{pmatrix}   &\times \begin{pmatrix}  -1& \\   0&\\  2&   \end{pmatrix} \\\\  =(-1*-1)+(-1*0)+(3*2))\\=1+0+6\\=7

Melody Mar 22, 2015
 #2
avatar+130477 
+5

 

 

Melody has given the dot product - a scalar - of these two vectors...

However....if the cross-product was wanted, we have

(-1,-1,3) x (-1,0,2) = (u1, u2, u3) x (v1, v2, v3)  = (s1, s2, s3)

 

\begin{align} s_1 &= u_2v_3-u_3v_2\\ s_2 &= u_3v_1-u_1v_3\\ s_3 &= u_1v_2-u_2v_1 \end{align}

 

s1 = [-1*2] - [3*0] = -2 - 0  = -2

s2 = [3*-1] - [-1*2]  =  -3 - (-2)  = -3 + 2 = -1

s3 = [-1*0] - [-1* -1 ] = 0 - 1  = -1

The cross-product produces a vector in three-space that is perpendicular to the given vectors, namely..... (-2, -1, -1)

 

   

 Mar 22, 2015
 #3
avatar+33657 
+5

Here's a picture of the vectors for the cross-product:

 cross product

.

 Mar 22, 2015
 #4
avatar+130477 
0

Thanks, Alan.....

 

  

 Mar 22, 2015

0 Online Users