Question

Difficulty: MediumDistance and Midpoint Formulas

On a coordinate grid, a line segment connects the points A(1,3)A(1, 3) and B(9,15)B(9, 15). The midpoint of this segment is MM, and the midpoint of the segment connecting AA and MM is CC. What is the yy-coordinate of point CC?

Answer: 6

Answer

The yy-coordinate of point CC is 6.
Applying the midpoint formula to the endpoints A(1,3)A(1, 3) and B(9,15)B(9, 15) yields M(5,9)M(5, 9). Applying the midpoint formula again to A(1,3)A(1, 3) and M(5,9)M(5, 9) yields C(3,6)C(3, 6). The yy-coordinate of point CC is therefore 6.

Step-by-Step Solution

1
Calculate the coordinates of the midpoint MM of segment ABAB.
M=(5,9)M = (5, 9)
The midpoint formula is defined as (x1+x22,y1+y22)\left(\frac{x_1 + x_2}{2}, \frac{y_1 + y_2}{2}\right).
2
Calculate the coordinates of the midpoint CC of segment AMAM.
C=(3,6)C = (3, 6)
Apply the midpoint formula using the coordinates of A(1,3)A(1, 3) and the newly found midpoint M(5,9)M(5, 9).
3
Identify the yy-coordinate of point CC.
6
For the point C(3,6)C(3, 6), the xx-coordinate is 3 and the yy-coordinate is 6.

Key Concept

Midpoint Formula
Estimated Time:1m 15s
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