Calculus Help

[buffgilville]

Find the minimum distance from the point where x = 20 along the x axis to the curve given by:
y= 3 * square root of (x-15)

My prof. has not gone over this yet, so can someone help me?

[Spectre5]

create a vector, measured from the origin that locates any point from the x = 2 mark to the line. Then find the magnitude of that vector (in terms of x). Differentiate that answer and set it equal to zero. Find your solution. Check to make sure it is a mininum and not a maximum.

Then you have your x value. Plug that value into the equation for the maginute of the vector, that is the distance