Points A and B are at (8 ,5 ) and (8 ,2 ), respectively. Point A is rotated counterclockwise about the origin by (3pi)/2 and dilated about point C by a factor of 3 . If point A is now at point B, what are the coordinates of point C?

1 Answer
May 28, 2018

C=(7/2,-13)

Explanation:

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

• " a point "(x,y)to(y,-x)

A(8,5)toA'(5,-8)" where A' is the image of A"

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

ulb-ulc=3(ula'-ulc)

ulb-ulc=3ula'-3ulc

2ulc=3ula'-ulb

color(white)(2ulc)=3((5),(-8))-((8),(2))

color(white)(2ulc)=((15),(-24))-((8),(2))=((7),(-26))

ulc=1/2((7),(-26))=((7/2),(-13))

rArrC=(7/2,-13)