A triangle has corners at (2, 7 ), ( 6, 3 ), and ( 2 , 5 ). If the triangle is dilated by 2 x around (2, 5), what will the new coordinates of its corners be?

1 Answer
Oct 11, 2016

(2,5),(10,1),(2,9)

Explanation:

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ABC is the original triangle. AB'C' is the dilated triangle.

Given: A(2,5), B(6,3), C(2,7)

1) Given the 2X dilation is around Pt A(2,5), A's coordinates remain unchanged at (2,5)

2) From Pt A(2,5) to Pt B(6,3)
Delta x = x_2-x_1=6-2=4
Delta y=y_2-y_1=3-5=-2
Given scaling factor =2X, => AB'=2AB
=> 2Deltax=2*4=8,
=>2Deltay=2*(-2)=-4

=> coordinates of B'=(2+8, 5-4)=(10,1)

3) From Pt A(2,5) to Pt C(2,7)
Delta x = x_2-x_1=2-2=0 (vertical line)
Delta y=y_2-y_1=7-5=2
Given scaling factor =2X, => AC'=2AC
=> 2Deltax=2*0=0,
=>2Deltay=2*2=4

=> coordinates of C'=(2+0, 5+4)=(2,9)

Hence, the new coordinates of the dilated triangle will be:
A(2,5), B'(10,1), C'(2,9)