Points A and B are at (1 ,5 )(1,5) and (2 ,3 )(2,3), respectively. Point A is rotated counterclockwise about the origin by (3pi)/2 3π2 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
Mar 14, 2018

C=(6,1/3)C=(6,13)

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)

rArrA(1,5)toA'(5,1)" where A' is the image of A"

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

rArrulb-ulc=4(ula'-ulc)

rArrulb-ulc=4ula'-4ulc

rArr3ulc=4ula'-ulb

color(white)(rArr3ulc)=4((5),(1))-((2),(3))

color(white)(rArr3ulc)=((20),(4))-((2),(3))=((18),(1))

rArrulc=1/3((18),(1))=((6),(1/3))

rArrC=(6,1/3)