Question

Which glide reflection describes the mapping triangle ABC --> triangle DEF?
A. (x, y) (x + 1, y – 2) and reflected across x = 0
B. (x, y) (x + 2, y – 1) and reflected across y = -1
C. (x, y) (x + 1, y – 2) and reflected across y = -1
D. (x, y) (x + 1, y – 2) and reflected across y = 0

Answer 1

Alright, lets get to it.

Answer 2

ok :)

Answer 3

Start off by comparing any one vertex of the triangle. For the sake of ease, lets choose A.

Answer 4

What is the vertex of the triangle DEF that corresponds to A?

Answer 5

D?

Answer 6

Correct. Now lets compare the co-ordinates of D and A. Can you see that the X co-ordinate of D is 1 greater than that of A? Similarly, its Y co-ordinate is different by....????

Answer 7

i have no idea

Answer 8

Ok look at it this way: To come to point D, A had to be shifted 1 unit to the left (in X direction). Similarly, how many units should it be shifted in the Y direction to arrive at D?

Answer 9

2?

Answer 10

Correct!! But its downward. So the correct answer is...+2 or -2?

Answer 11

-2

Answer 12

Right!! Now you have a part of the answer. Now all that remains, is that how exactly do you get that new triangle? Well, if you observe, the new triangle is simply the old one turned upside down! Now about which axis can you turn it like that?

Answer 13

the x-axis?

Answer 14

Right you are!!! There you go!

Answer 15

& the answer is a, right?

Answer 16

Yup it is!!

Answer 17

so would this one be A or D?