Exercise 43 Page 669

Let's start by plotting the given points on a coordinate plane and drawing triangle △ ABC.

We are asked to find the coordinates of the centroid of △ ABC. This is the point of concurrency of the triangle's medians. A median of a triangle is a segment with one endpoint being a vertex and the other endpoint being the midpoint of the opposite side. cc Vertex & Opposite Side [0.8em] C & AB A & BC B & CA Let's find the medians of △ ABC and then we can find their point of intersection.

Median of AB

First, we will find the midpoint of AB by substituting the coordinates of A and B into the Midpoint Formula. Now that we know the coordinates of the midpoint of AB, we can plot this point on our diagram. Let's name this point N. Drawing a segment from C to N, we will get the median of AB.

Median of BC

Using the same process, we can find the midpoint of BC. This time we will substitute the coordinates of B and C into the Midpoint Formula. Now, let's plot the midpoint of BC at (- 7,3.5) and name it K. If we draw a segment from K to vertex A, we will have the median of BC.

Median of CA

One last time, we will follow the same procedure — this time using the coordinates of A and C. Let's name this midpoint L and add it to the diagram. The segment that connects B and L is a median of AC.

Coordinates of the Midpoint

As we can see on our diagram, the medians intersect at point (- 5,6). These are the coordinates of the centroid of △ ABC.