Confusion with Locus (1 Viewer)

[love2eight]

I can't seem to understand how to get the answer to this question:

Find the equation of the normal to the curve x^2=12y at the point (6,3). This normal meets the parabla again at point P. Find the coordinates of Point P...

How do I find P? :S

 

[morganforrest]

y= 1/12x^2
y'=1/6x

y'(6)=1

gradient of normal is -1/m
-1/1 = -1

use point gradient formula
y-3=x+6
y=x+9

solve simultaneuously to find where the normal meets the parabola

x+9=1/12x^2
x^2-12x-108=0

factorise to find the two places where it cuts the parabola
One answer will be (6,3)
The other answer will be P

 

[love2eight]

aah i see.. thanks

 

[forevaunited]

Is that a locus question? I get confused with 2unit Locus. The only thing i can remember is that you have to "let x = something". Or is that 3unit? Can somebody clear this up for me? What are the types of locus questions that can be examined?