[Math] Find the point on the plane $2x – y + 2z = 20$ nearest the origin

multivariable-calculus

What I did was use the distance formula from the plane to the origin, found the normal vector, and found the unit vector of the normal vector. I multiplied the unit vector by the distance to get the point (and it satisfies the equation). Is this correct?

Is there a way of doing this using optimization (i.e. local min/max)?

Best Answer

Sounds right.

Yes, you can do this by minimization. First write down the distance of a general point from the origin (hint: it is simple). Then you want to minimize that function subject to the constraint given by the plane.

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