Question 1114879
If {{{u}}} is the scalar value for the velocity vector {{{u}}},
{{{abs(u)=sqrt(u[x]^2+u[y]^2+u[z]^2)}}}
Substituting,
{{{u=sqrt((u*sin(theta))^2+(u*cos(theta))^2+u[z]^2)}}}
{{{u^2=u^2*sin^2(theta)+u^2*cos^2(theta)+u[2]^2}}}
{{{u^2=u^2(sin^2(theta)+cos^2(theta))+u[z]^2}}}
{{{u^2=u^2(1)+u[z]^2}}}
{{{u^2=u^2+u[z]^2}}}
{{{u[z]^2=0}}}
{{{u[z]=0}}}