Tangent points to 2 surfaces: x^2-xy+z=0 and (x-1)^2+(y+1)^2+z=10

tparker73

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Problem is: find points where surfaces x^2-xy+z=0 and (x-1)^2+(y+1)^2+z=10 are tangent.

I get as far as finding the gradients of each but can't figure out where to go from there. Anyone have an idea?

Thanks.
 
Problem is: find points where surfaces x^2-xy+z=0 and (x-1)^2+(y+1)^2+z=10 are tangent.

I get as far as finding the gradients of each but can't figure out where to go from there. Anyone have an idea?

Thanks.

F(x,y,z)= x^2-xy+z
G(x,y,z)= (x-1)^2+(y+1)^2+z

Gradient of F = <2x-y, -x, 1>

Gradient of G = <2(x-1), 2(y+1), 1>

I need to find the point or points where these two level surfaces are tangent. I feel like I need to do a cross product of these somewhere but I am lost as to what the next step is.
 
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F(x,y)= x^2-xy+z ← LHS says F is function of two variables. However RHS has three variables.

G(x,y)= (x-1)^2+(y+1)^2+z← LHS says G is function of two variables. However RHS has three variables.
Check your definitions carefully.

Gradient of F = <2x-y, -x, 1>

Gradient of G = <2(x-1), 2(y+1), 1>

I need to find the point or points where these two level surfaces are tangent. I feel like I need to do a cross product of these somewhere but I am lost as to what the next step is.
.
What is the relationship between the gradient of a function and the normal to the tangent plane?
 
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