A triangle has corners at #(5 ,2 )#, #(9 ,7 )#, and #(3 ,5 )#. How far is the triangle's centroid from the origin?

1 Answer
Jun 7, 2016

#1/3sqrt485≈7.34#

Explanation:

The first step here is to find the coordinates of the centroid using the following.

Given 3 vertices of a triangle # (x_1,y_1),(x_2,y_2),(x_3,y_3)#

x-coordinate #(x_c)=1/3(x_1+x_2+x_3)#

and y-coordinate #(y_c)=1/3(y_1+y_2+y_3)#

using the coordinates given in the question

#rArrx_c=1/3(5+9+3)=17/3#

and #y_c=1/3(2+7+5)=14/3#

hence coordinates of centroid #=(17/3,14/3)#

To calculate the distance from the origin use the #color(blue)" distance formula"#

#color(red)(|bar(ul(color(white)(a/a)color(black)(d=sqrt((x_2-x_1)^2+(y_2-y_1)^2))color(white)(a/a)|)))#
where #(x_1,y_1)" and " (x_2,y_2)" are 2 points"#

The 2 points here are (0 ,0) and #(17/3,14/3)#

#d=sqrt((17/3-0)^2+(14/3-0)^2)=sqrt((17/3)^2+(14/3)^2)#

#=sqrt(289/9+196/9)=1/3sqrt485≈7.34#