Saturday

April 19, 2014

April 19, 2014

Posted by **Luisa** on Friday, October 12, 2007 at 8:32pm.

a) Write an equation for each of the three medians

b) Recall that the centroid of a triangle is the point of intersection of the medians of the triangle. Use the equations from part a) to verify that (4,0) is the centroid of triangle XYZ.

I've been trying to solve this problem for over an hour and the equations I'm getting for part a) don't match the answers in tha back of my book, y=0, x-4=0, and x+y-4=0. I really need some help, please

- Math -
**Reiny**, Friday, October 12, 2007 at 8:48pmLet the midpoints of XY,YZ, and XZ be P,Q, and R respectively

Did you get P(2,2), Q(6,0) and R(4,-2) ?

XQ is obviously y = 0, the equation of the x-axis

YR has undefined slope, so its equation is x=4

Right there you already have the coordinates of the centroid, namely (4,0)

the slope of PZ is (-4-2)/(8-2) = -1

so y=-x+b, sub in (2,2) for

2=-2+b

b=4

so y = -x + 4

(notice that (4,0) satisfies this last median equation.

BTW, a quick way to find the centroid if you know the three vertices of a triangle...

centroid = (sum of x values/3,sum of y values/3)

- Math -
**Luisa**, Friday, October 12, 2007 at 8:52pmoh, thank you so much!

it all makes sense now, my book was just so confusing on the topic and I cannot even begin to express hoe grateful I am; I was so desperate and overwhlemed by this.

Thank you!

**Related Questions**

geometry - The medial triangle of a triangle ABC is the triangle whose vertices...

physics - three point charges each of magnitude +q are located at the vertices ...

math - If the adjacent vertices of a square ABCD are A ( -2 , 0 ) , find - The ...

Geometry - Given a triangle ABC with A(6b,6c) B(0,0) and C (6a,0), prove that ...

Geometry - what are the coordinates of the centroid of each triangle given the ...

geometry - show that the sum of the squares of the lengths of the medians of ...

math - in a triangle BCA there are three medians b,c,a. Prove that 3(A^2+B^2+C^2...

Geometry: Ms. Sue or Steve or someone help please? - Given a triangle ABC with A...

pre-calculus - triangle KLM has vertices K(0,0), L(18,0), and M(6,12). a. Write ...

math - the verticies of triangle R(0,12), S(-6,6), and T(4,8). write in slope-...