Points A and B are at (6 ,1 )(6,1) and (8 ,9 )(8,9), respectively. Point A is rotated counterclockwise about the origin by pi π and dilated about point C by a factor of 3 3. If point A is now at point B, what are the coordinates of point C?
1 Answer
Oct 4, 2017
Explanation:
"under a counterclockwise rotation about the origin of "piunder a counterclockwise rotation about the origin of π
• " a point "(x,y)to(-x,-y)∙ a point (x,y)→(−x,−y)
rArrA(6,1)toA'(-6,-1)" where A' is the image of A"
"under a dilatation about C of factor 3"
vec(CB)=3vec(CA')
rArrulb-ulc=3(ula'-ulc)
rArrulb-ulc=3ula'-3ulc
rArr2ulc=3ula'-ulb
color(white)(rArr2ulc)=3((-6),(-1))-((8),(9))
color(white)(rArrulc)=((-18),(-3))-((8),(9))=((-26),(-12))
rArrulc=1/2((-26),(-12))=((-13),(-6))
rArrC=(-13,-6)