Points A and B are at (9 ,7 ) and (3 ,4 ), respectively. Point A is rotated counterclockwise about the origin by pi/2 and dilated about point C by a factor of 2 . If point A is now at point B, what are the coordinates of point C?
1 Answer
Feb 17, 2018
Explanation:
"under a counterclockwise rotation about the origin of "pi/2
• " a point "(x,y)to(-y,x)
rArrA(9,7)toA'(-7,9)" where A' is the image of A"
rArrvec(CB)=color(red)(2)vec(CA')
rArrulb-ulc=2(ula'-ulc)
rArrulb-ulc=2ula'-2ulc
rArrulc=2ula'-ulb
color(white)(rArrulc)=2((-7),(9))-((3),(4))
color(white)(rArrulc)=((-14),(18))-((3),(4))=((-17),(14))
rArrC=(-17,14)