# Calculus III: Vector Functions and Space Curves

• Sep 22nd 2008, 06:26 PM
saxyliz
Calculus III: Vector Functions and Space Curves
If someone could please help me with this problem it would be most appreciated! I don't even know where to start!

Find a vector function that represents the curve of intersection of the two surfaces (in the 3D space):

The paraboloid: $z = 4x^2 + y^2$
The parabolic cylinder: $y = x^2$
• Sep 22nd 2008, 06:29 PM
Jhevon
Quote:

Originally Posted by saxyliz
If someone could please help me with this problem it would be most appreciated! I don't even know where to start!

Find a vector function that represents the curve of intersection of the two surfaces (in the 3D space):

The paraboloid: $z = 4x^2 + y^2$
The parabolic cylinder: $y = x^2$

plug in $y = x^2$ into $z$, so that $z = 4x^2 + x^4$

now parametrize the curve using $x = t$ as the parameter
• Sep 22nd 2008, 06:37 PM
saxyliz
What exactly do to mean by "parametrize the curve?"

Is it:
$z = 4t^2 + t^4$
?
• Sep 22nd 2008, 06:40 PM
Jhevon
Quote:

Originally Posted by saxyliz
What exactly do to mean by "parametrize the curve?"

Is it:
$z = 4t^2 + t^4$
?

the vector function is $r(t) = \left< x(t), y(t), z(t) \right> = \left< t, t^2 , 4t^2 + t^4 \right>$
• Sep 22nd 2008, 06:44 PM
saxyliz
Oh! I get it now! Thanks a lot!