Points A and B are at (7 ,9 )(7,9) and (6 ,8 )(6,8), respectively. Point A is rotated counterclockwise about the origin by (3pi)/2 3π2 and dilated about point C by a factor of 2 2. If point A is now at point B, what are the coordinates of point C?

1 Answer
Jun 27, 2018

C=(12,-22)C=(12,22)

Explanation:

"under a counterclockwise rotation about the origin of "(3pi)/2under a counterclockwise rotation about the origin of 3π2

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

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

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

ulb-ulc=2(ula'-ulc)

ulb-ulc=2ula'-2ulc

ulc=2ula'-ulb

color(white)(ulc)=2((9),(-7))-((6),(8))

color(white)(ulc)=((18),(-14))-((6),(8))=((12),(-22))

rArrC=(12,-22)