Posted by **Anonymous** on Sunday, October 14, 2012 at 11:58am.

Triangle with vertices:

D(-18,12)

E(-6,-12)

F(12,6)

Show that the right bisectors of the sides of triangleDEF all intersect at point C(-4,4), the circumcentre of the triangle.

-I found the midpoint of DF then the slope of the midpoint and point E, then found y intercept of new point (midpoint I labelled A) I then subbed point C into the equation of the line found. But it doesn't seem to be equally each other as they should...help!

- Math -
**Reiny**, Sunday, October 14, 2012 at 12:40pm
Problem #1 is that you are not finding the right-bisector, but rather the medians

I will describe the steps to find your first right-bisector

1. the midpoint of DF is A(-3, 9)

2. slope of DF = 6/-30 = - 1/5

3. So the slope of the right-bisector of DF is +5

4. equation of right-bisector is

y = 5x + b , but A(-3,9) lies on it, so

9 = 5(-3) + b

b = 24

right-bisector of DF is y = 5x + 24

repeat those steps for one of the other sides

solve those two equations, you should get (-4,4)

Find the equation of the third side, using the above steps

Sub in (-4,4) to see if it satisfies the third equation, it should !!

- Math -
**Anonymous**, Sunday, October 14, 2012 at 1:15pm
Thanks!!

## Answer This Question

## Related Questions

- pre-calculus - triangle KLM has vertices K(0,0), L(18,0), and M(6,12). a. Write ...
- GEOMETRY ONE QUESTION PLEASE HELP!!!!! - Where is the circumcenter of any given ...
- MATH - When a draftsman draws three lines that are to intersect at one ...
- Math - Triangle AOB has vertices A(4,4), O(0,0), and B(8,0). EF right bisects AB...
- Math - 1. Where is the incenter of any given triangle? A) the point of ...
- math plz check ;-; - A triangle has sides of lengths 5 cm, 5 cm, and square root...
- math plz check ;-; sorry - A triangle has sides of lengths 5 cm, 5 cm, and ...
- geometry - In triangle ABC, X and Y are the midpoints of BC and AC, respectively...
- Algebra - Find the coordinates of the midpoint of the hypotenuse of the right ...
- geometry - the vertices of triangle ABC are A(1,7)B(9,3)C(3,1) a.prove that the ...

More Related Questions