# Coordinate Geometry

• Oct 19th 2010, 05:54 PM
buck
Coordinate Geometry
So there is this question on the homework that I don't quite get, could you please help me out?

Beibou is designing a parking lot. A tall mast light will illuminate the three entrances, which will be located at points A(-8,13), B(-4,8) and C(18,10). Beibou needs to position the lamp so that it illuminates each entrance equally.
• Oct 19th 2010, 05:59 PM
skeeter
Quote:

Originally Posted by buck
So there is this question on the homework that I don't quite get, could you please help me out?

Beibou is designing a parking lot. A tall mast light will illuminate the three entrances, which will be located at points A(-8,13), B(-4,8) and C(18,10). Beibou needs to position the lamp so that it illuminates each entrance equally.

let A, B, and C be three points on a circle whose center will be located where the perpendicular bisectors of AB and BC intersect.
• Oct 19th 2010, 06:03 PM
buck
:S I graphed it out A, B, and C and it is a triangle, AB and BC intersect perpendicular?
• Oct 19th 2010, 09:42 PM
bigwave
3 simultaneous circle equations
I did probably did it the hardest way

3 simultaneous circle equations set them to each other since the radius is the same

$(x+8)^2+(y-13)^2=(x+4)^2+(y-8)^2=(x-18)^2+(y-10)^2$

$x = \frac{707}{118}$

$y = \frac{2371}{118}$

not nice even answers but they seem to be where the center is.(Cool)
• Oct 20th 2010, 11:21 AM
skeeter
Quote:

Originally Posted by buck
:S I graphed it out A, B, and C and it is a triangle, AB and BC intersect perpendicular?

... that is not what I posted.