Let D(x, y) be the midpoints of A(6, 8) and B(2, 4). Let our third given point be C(1, 2).
By midpoint formula.
x = \(\frac{x_1+x_2}2\), y = \(\frac{y_1+y_2}2\)
For midpoint D of AB,
x = \(\frac{6+2}2\) and y = \(\frac{8+4}2\)
∴ x =4 and y = 6
∴D(x, y) ≡ (4, 6)
Now to find distance between C and D,
By distance formula,
XY = \(\sqrt{(x_2-x_1)^2+(y_2-y_1)^2}\)
For CD,
CD = \(\sqrt{(4-1)^2+(6-2)^2}\)
= \(\sqrt{9 + 16}\)
= 5 units