Lesson 16

Weighted Averages in a Triangle

  • Let’s partition special line segments in triangles.

Problem 1

Triangle \(ABC\) and its medians are shown.

Triangle ABC graphed. A = -2 comma 0, B = 0 comma 4, C = 3 comma 2. median CD, D = -1 comma 2. median BF, F = 0 point 5 comma 1. median AE, E = 1 point 5 comma 3. 

Select all statements that are true.


The medians intersect at \(\left(\frac{1}{3}, 2\right)\).


The medians and altitudes are the same for this triangle.


An equation for median \(AE\) is \(y=\frac{6}{7}(x+2)\).


Point \(G\) is \(\frac{2}{3}\) of the way from \(A\) to \(E\).


Median \(BF\) is congruent to median \(CD\).

Problem 2

Triangle \(ABC\) has vertices at \((\text-2,0), (\text-1,6),\) and \((6,0)\). What is the point of intersection of the triangle’s medians?

Problem 3

Triangle \(EFG\) and its medians are shown.

Triangle EFG and its medians EH, FI, and GJ drawn.

Match each pair of segments with the ratios of their lengths.

Problem 4

Given \(A=(\text-3,2)\) and \(B=(7,\text-10)\), find the point that partitions segment \(AB\) in a \(1:4\) ratio.

(From Unit 6, Lesson 15.)

Problem 5

Graph the image of quadrilateral \(ABCD\) under a dilation using center \(A\) and scale factor \(\frac{1}{3}\).

Quadrilateral ABCD. Point A at 0 comma 0. Point B at 10 comma 6. Point C at 12 comma 18. Point D at negative 6 comma 6.
(From Unit 6, Lesson 15.)

Problem 6

A trapezoid is a quadrilateral with at least one pair of parallel sides. Show that the quadrilateral formed by the vertices \((0,0), (5,2), (10,10),\) and \((0,6)\) is a trapezoid.

(From Unit 6, Lesson 14.)

Problem 7

Here are the graphs of the circle centered at \((0,0)\) with radius 6 units and the line given by \(2x+y=11\). Determine whether the circle and the line intersect at the point \((3,5)\). Explain or show your reasoning.

Graph of circle with center 0 comma 0, radius 6 units. Line is 2x plus y equals 11.
(From Unit 6, Lesson 13.)

Problem 8

A parabola has focus \((\text-3,2)\) and directrix \(y=\text-3\). The point \((a,5)\) is on the parabola. How far is this point from the focus?


8 units


5 units


3 units


2 units

(From Unit 6, Lesson 8.)