Parametrics Query (2 Viewers)

[Finx]

Find the equation of the locus of a point P (xy) that moves so that it is always 4 units from the point (-3,2).

These are the exact words of the question, though I think it meant P(x,y), not (xy).

I first thought the locus would be a circle with radius 4 and center point (-3,2), giving the equation (x+3)² + (y-2)² = 16.

I only came to this conclusion from basic logic, I'm not sure how I can show it in working.

Little help please? Thanks =]

 

[shady145]

you are correct.
the only working out you could do is write the formula first and then sub in your pts.

 

[Finx]

you are correct.
the only working out you could do is write the formula first and then sub in your pts.

As in writing the circle formula?

Are you sure I can write "By logic, the locus is a circle" and achieve full marks?

 

[independantz]

Find the equation of the locus of a point P (xy) that moves so that it is always 4 units from the point (-3,2).

d=sqrt[(x₂-x₁)²+(y₂-y₁)²)]-distance formula.

4=sqrt{(x+3)²+(y-2)²}
16=(x+3)²+(y-2)²

 

[Finx]

I love you. Thanks!