Points A and B are at (8 ,2 )(8,2) and (3 ,7 )(3,7), respectively. Point A is rotated counterclockwise about the origin by pi/2 π2 and dilated about point C by a factor of 3 3. If point A is now at point B, what are the coordinates of point C?

1 Answer
Feb 26, 2018

C=(-9/2,17/2)C=(92,172)

Explanation:

"under a counterclockwise rotation about the origin of "pi/2under a counterclockwise rotation about the origin of π2

• " a point "(x,y)to(-y,x) a point (x,y)(y,x)

rArrA(8,2)toA'(-2,8)" where A' is the image of A"

rArrvec(CB)-color(red)(3)vec(CA')

rArrulb-ulc=3(ula'-ulc)

rArrulb-ulc=3ula'-3ulc

rArr2ulc=3ula'-ulb

color(white)(rArr2ulc)=3((-2),(8))-((3),(7))

color(white)(rArr2ulc)=((-6),(24))-((3),(7))=((-9),(17))

rArrulc=1/2((-9),(17))=((-9/2),(17/2))

rArrC=(-9/2,17/2)