Points A and B are at (3 ,7 )(3,7) and (2 ,4 )(2,4), respectively. Point A is rotated counterclockwise about the origin by pi/2 π2 and dilated about point C by a factor of 4 4. If point A is now at point B, what are the coordinates of point C?

1 Answer
Jun 30, 2018

C=(-10,8/3)C=(10,83)

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)

A(3,7)toA'(-7,3)" where A' is the image of A"

vec(CB)=color(red)(4)vec(CA')

ulb-ulc=4(ula'-ulc)

ulb-ulc=4ula'-4ulc

3ulc=4ula'-ulb

color(white)(3ulc)=4((-7),(3))-((2),(4))

color(white)(3ulc)=((-28),(12))-((2),(4))=((-30),(8))

ulc=1/3((-30),(8))=((-10),(8/3))

rArrC=(-10,8/3)