- #1
badgers14
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Let M be the surface defined by z=x2+3xy-5y2. Find a unit normal vector field U defined on a neighborhood of p on M.
First, I reparameterized the equation for the surface to get x(u,v)=(u,v,u2+3xy-5y2). Next I found two tangent vectors xu(u,v)=(1,0,2u+3v) and xv=(0,1,3u-10v). The next step is where I'm unsure. In the text it gives an equation for the unit normal function, U=(xu X xv)/||xu X xv||. When I use this equation, I come up with
U=(-2u-3v,10v-3u,1)/(sqrt(13u2-54uv+109v2+1)
This just seemed messy to me, not sure if I'm missing something or if that is actually what the answer should look like. Any verification/help would be appreciated
First, I reparameterized the equation for the surface to get x(u,v)=(u,v,u2+3xy-5y2). Next I found two tangent vectors xu(u,v)=(1,0,2u+3v) and xv=(0,1,3u-10v). The next step is where I'm unsure. In the text it gives an equation for the unit normal function, U=(xu X xv)/||xu X xv||. When I use this equation, I come up with
U=(-2u-3v,10v-3u,1)/(sqrt(13u2-54uv+109v2+1)
This just seemed messy to me, not sure if I'm missing something or if that is actually what the answer should look like. Any verification/help would be appreciated