Points A and B are at (3 ,5 )(3,5) and (6 ,1 )(6,1), 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
Mar 21, 2018

C=(-21/2,4)C=(212,4)

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(3,5)toA'(-5,3)" 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((-5),(3))-((6),(1))

color(white)(rArr2ulc)=((-15),(9))-((6),(1))=((-21),(8))

rArrulc=1/2((-21),(8))=((-21/2),(4))

rArrC=(-21/2,4)