Big Ideas Math Geometry, 2014
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Big Ideas Math Geometry, 2014 View details
Chapter Review
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Exercise 7 Page 351

Consider the Centroid Theorem.

(-6,3)

Practice makes perfect

Let's begin by plotting the triangle in a coordinate plane using the given coordinates.

To find the centroid of a triangle, we should first determine the midpoint of each side. We can do that using the Midpoint Formula.

Side Points M(x_1+x_2/2,y_1+y_2/2) Midpoint
AB ( -10,3), ( -4,5) D(-10+( -4)/2,3+ 5/2) D(-7,4)
AC ( -10,3), ( -4,1) E(-10+( -4)/2,3+ 1/2) E(-7,2)
BC ( -4,5), ( -4,1) F(-4+( -4)/2,5+ 1/2) F(-4,3)

Let's add these midpoints to our graph.

According to the Centroid Theorem, the centroid of a triangle is two-thirds of the distance from a vertex to the midpoint of the opposite side. Note that the midpoint F(-4,3) shares a y-coordinate with the vertex A. This allows us to calculate the distance as the difference between x-coordinates. 2/3( F_x- A_x)=2/3( -4-( -10)) Let's find the distance.
2/3(-4-(-10))
â–Ľ
Simplify
2/3(6)
12/3
4
This calculation tells us that the centroid is 4 units from vertex A along the median. In this case, the median is AF.

We can see that the coordinates of the centroid are (-6,3).