# [SOLVED] Equation of the tangent plane to a parametrized surface

• May 28th 2009, 05:11 PM
Anxiety35
[SOLVED] Equation of the tangent plane to a parametrized surface
I'm pretty sure I'm making a small mistake on these problems. I've done several they way I'm sure it's done, and rechecked them and they always come back as incorrect.
Here's an example problem:

$r(u,v) = (-3u, 2u^2-4v, 5v^2)$ at the point (9, 6, 45)

From this I get that:
$(u,v) = (-3,3)$
$r_u = (-3,-12,0)$
$r_v = (0, -4, 30)$

$-360x - 90y + 12z + 3240 = 0$

How far off am I? I can post all my steps if needed.
Thanks.
• May 28th 2009, 05:26 PM
Anxiety35
Nevermind. I was doing the cross product wrong. I was forgetting to switch the signs for it. Arg, so much frustration over that little issue.