Posted by **Josh** on Wednesday, January 20, 2010 at 7:01pm.

Find all the points having an x coordinate of 2 whose distance from the point (-1,-5) is 5.

so far i have

5=sqrt((-1-2)^2+(-2-y)^2)

5=(-3)^2

how do i simplify the rest of the equation so i can find x. do i foil it out? thanks.

- Trig/Math -
**MathMate**, Wednesday, January 20, 2010 at 8:09pm
Geometrically, you are looking for the intersection of a vertical line (x=2) with a circle centred at (-1,-5) with a radius of 5.

Line L1: x=2

Circle C1: (x-(-1))²+(y-(-5))²=5²

(x+1)²+(y+5)²=25

Substitute x=2 in C1:

(2+1)²+(y+5)²=25

(y+5)²=25-3²=16=4²

(y+5) = ±4

So there are two solutions, y=-9 or y=-1

- Trig/Math -
**Josh**, Wednesday, January 20, 2010 at 10:27pm
thank you!!

- Trig/Math :) -
**MathMate**, Thursday, January 21, 2010 at 12:11am
You're welcome.

Do give a check on the distance between the centre and the intersection points to complete the question.

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