Points A and B are at (8 ,3 ) and (5 ,4 ), respectively. Point A is rotated counterclockwise about the origin by pi/2 and dilated about point C by a factor of 2 . If point A is now at point B, what are the coordinates of point C?

1 Answer
Jun 8, 2018

C(-11,12)

Explanation:

"under a counterclockwise rotation about the origin of "pi/2

• " a point "(x,y)to(-y,x)

A(8,3)toA'(-3,8)" where A' is the image of A"

vec(CB)=color(red)(2)vec(CA')

ulb-ulc=2(ula'-ulc)

ulb-ulc=2ula'-2ulc

ulc=2ula'-ulb

color(white)(ulc)=2((-3),(8))-((5),(4))

color(white)(ulc)=((-6),(16))-((5),(4))=((-11),(12))

rArrC=(-11,12)