given the vectors u x1 y1 z1 v x2 y2 z2 and w x3 y3 z3 Sh
given the vectors u = (x1, y1, z1), v = (x2, y2, z2) and w = (x3, y3, z3). Show that u (v x w) = (u x v) .w ?
Solution
u = x1, y1, z1,
v = x2, y2, z2 ,
w = x3, y3, z3
(vxw)=(y2z3-y3z2),(x3z2-x2z3),(x2y3-x3y2)
(uxv)=(y1z2-y2z1),(x2z1-x1z2),(x1y2-x2y1)
u.(vxw)= x1, y1, z1.(y2z3-y3z2),(x3z2-x2z3),(x2y3-x3y2) =x1(y2z3-y3z2)+ y1(x3z2-x2z3) +z1(x2y3-x3y2)
u.(vxw)=x1y2z3-x1y3z2+ x3y1z2-x2y1z3 +x2y3z1-x3y2z1
(uxv).w=(y1z2-y2z1),(x2z1-x1z2),(x1y2-x2y1)x3, y3, z3
(uxv).w=(y1z2-y2z1)x3+(x2z1-x1z2)y3+(x1y2-x2y1)z3
(uxv).w=x3y1z2-x3y2z1+x2y3z1-x1y3z2+x1y2z3-x2y1z3
(uxv).w=x1y2z3-x1y3z2+ x3y1z2-x2y1z3 +x2y3z1-x3y2z1
so u (v x w) = (u x v) .w
