Points A and B are at (1 ,7 ) and (3 ,9 ), respectively. Point A is rotated counterclockwise about the origin by (3pi)/2 and dilated about point C by a factor of 5 . If point A is now at point B, what are the coordinates of point C?

1 Answer
May 1, 2018

C=(8,-7/2)

Explanation:

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

• " a point "(x,y)to(y,-x)

rArrA(1,7)toA'(7,-1)" where A' is the image of A"

rArrvec(CB)=color(red)(5)vec(CA')

rArrulb-ulc=5(ula'-ulc)

rArrulb-ulc=5ula'-5ulc

rArr4ulc=5ula'-ulb

color(white)(rArr4ulc)=5((7),(-1))-((3),(9))

color(white)(rArr4ulc)=((35),(-5))-((3),(9))=((32),(-14))

rArrulc=1/4((32),(-14))=((8),(-7/2))

rArrC=(8,-7/2)