Question

A triangle has vertices (1, 4), (1, 1), and (−3, 1). The triangle is dilated by a scale factor of 2
then translated 5 units up, and then rotated 90° counterclockwise about the origin. What are the vertices of the image of the triangle?

Answer 1

i think what i'm supposed to do is add 5 to the y coordinates, multiply each x and y by 2, and for rotation flip the x and y and make the y negative

Answer 2

but im not sure

Answer 3

scale by 2 first

Answer 4

then add 5 to ys

Answer 5

then some magical rotation :)

Answer 6

to scale by 2 would i just multiply by 2? e.g. (1,4)->(2,8)

Answer 7

yes

Answer 8

okay and to rotate do i go from (x,y) to (-y,x)?

Answer 9

maybe, i can never recall that part .... i know the algebraic setup tho

new x = x cos(90) - y sin(90)
new y = x cos(90) + y sin(90)

seems about right

Answer 10

alright i can do that. thank you!