A line segment has endpoints at (3 ,5 ) and (6 ,1 ). The line segment is dilated by a factor of 4 around (6 ,2 ). What are the new endpoints and length of the line segment?

1 Answer
Feb 20, 2018

New points A’ ((-6),(14)), B’ ((6),(-2))

Length of the line segment after dilation vec(A’B’) = 18.44

Explanation:

A (3, 5), B ( 6, 1). Dilated around C (6,2 by factor 4.

vec (A’C) = 4 * vec(AC)

A’ - c= 4 * (a - c)

A’ = 4a - 3c

A’((x),(y)) = 4 ((3),(5)) - 3((6),(2)) = ((12),(20)) - ((18),(6)) = ((-6),(14))

A’ ((-6),(14))

Similarly,

vec(B’C) = 4 vec(AB)

B’((x),(y)) = 4((6),(1)) - 3((6),(2)) = ((24),(4)) - ((18),(6)) = ((6),(-2))

B’ ((6),(-2))

Using distance formula, vec(AB) = sqrt((3-6)^2 + (5-1)^2) = 5

vec(A’B’) = sqrt((-6-6)^2 + (14+2)^2) ~~ 18.44