http://www.ck12.org Chapter 5. Relationships with Triangles
- Find the midpoint ofABand label itM.
- Write the equation of
←→
CM.
- Find the midpoint ofBCand label itN.
- Write the equation of
←→
AN.
- Find the intersection of
←→
CMand←→
AN.
- What is this point called?
Another way to find the centroid of a triangle in the coordinate plane is to find the midpoint of one side and then
find the point two thirds of the way from the third vertex to this point. To find the point two thirds of the way from
pointA(x 1 ,y 1 )toB(x 2 ,y 2 )use the formula:
(
x 1 + 2 x 2
3 ,y 1 + 2 y 2
3)
. Use this method to find the centroid in the following
problems.
- (-1, 3), (5, -2) and (-1, -4)
- (1, -2), (-5, 4) and (7, 7)
- (2, -7), (-5, 1) and (6, -9)