A line segment has endpoints at (5 ,9 ) and (6 ,7 ). The line segment is dilated by a factor of 2 around (5 ,3 ). What are the new endpoints and length of the line segment?

1 Answer
Jul 27, 2018

(5,15),(7,11),2sqrt5

Explanation:

"let "A=(5,9),B=(6,7)" and "C=(5,3)" then"

vec(CA')=2vec(CA)" where A' is the image of A"

ula'-ulc=2ula-2ulc

ula'=2ula-ulc

color(white)(ula')=2((5),(9))-((5),(3))

color(white)(ula')=((10),(18))-((5),(3))=((5),(15))

rArrA'=(5,15)

"Similarly "

ulb'=2ulb-ulc

color(white)(ulb')=2((6),(7))-((5),(3))

color(white)(ulb')=((12),(14))-((5),(3))=((7),(11))

rArrB'=(7,11)

"calculate the length using the "color(blue)"distance formula"

•color(white)(x)d=sqrt((x_2-x_1)^2+(y_2-y_1)^2)

"let "(x_1,y_1)=(7,11)" and "(x_2,y_2)=(5,15)

d=sqrt((5-7)^2+(15-11)^2

color(white)(d)=sqrt(4+16)=sqrt20=2sqrt5