Points A and B are at (2 ,9 )(2,9) and (3 ,2 )(3,2), 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
Jun 5, 2017

C=(-15,2)C=(15,2)

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(2,9)toA'(-9,2)" where " A' " is the image of A"

"Under a dilatation about " C" of factor 3"

vec(CB)=color(red)(3)vec(CA')

rArrulb-ulc=color(red)(3)(ula'-ulc)

rArrulb-ulc=3ula'-3ulc

rArr2ulc=3ula'-ulb

color(white)(rArr2cx)=3((-9),(2))-((3),(2))=((-30),(4))

rArrulc=1/2((-30),(4))=((-15),(2))

rArrC=(-15,2)