Points A and B are at (9 ,7 ) and (3 ,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
Feb 17, 2018

C=(-17,14)

Explanation:

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

• " a point "(x,y)to(-y,x)

rArrA(9,7)toA'(-7,9)" where A' is the image of A"

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

rArrulb-ulc=2(ula'-ulc)

rArrulb-ulc=2ula'-2ulc

rArrulc=2ula'-ulb

color(white)(rArrulc)=2((-7),(9))-((3),(4))

color(white)(rArrulc)=((-14),(18))-((3),(4))=((-17),(14))

rArrC=(-17,14)