Question

Triangle ABC has coordinates A(1,-1), B(0,2), and C(2,1) and it is reflected over the line y = x to form triangle A'B'C'. What are the coordinates of triangle A'B'C answer the question using complete sentences...please help

Answer 1

The coordinates of triangle A'B'C' are A' (-1 , 1) , B' (2 , 0) , C' (1 , 2)

Explanation:

* Lets revise some transformation

- If point (x , y) reflected across the x-axis

∴ Its image is (x , -y)

- If point (x , y) reflected across the y-axis

∴ Its image is (-x , y)

- If point (x , y) reflected across the line y = x

∴ Its image is (y , x)

- If point (x , y) reflected across the line y = -x

∴ Its image is (-y , -x)

* Lets solve the problem

- ABC is a triangle, where A = (1 , -1) , B = (0 , 2) , C = (2 , 1)

- The Δ ABC reflected over the line y = x to form ΔA'B'C'

∵ The image of the point (x , y) after reflected across the line y = x

is (y , x)

∴ We will switch the coordinates of each point in Δ ABC to find the

coordinates of Δ A'B'C'

# Vertex A

∵ A = (1 , -1) ⇒ x = 1 , y = -1

∴ The x-coordinate of the image is -1

∴ The y-coordinate of the image is 1

∴ A' = (-1 , 1)

# Vertex B

∵ B = (0 , 2) ⇒ x = 0 , y = 2

∴ The x-coordinate of the image is 2

∴ The y-coordinate of the image is 0

∴ B' = (2 , 0)

# vertex C

∵ C = (2 , 1) ⇒ x = 2 , y = 1

∴ The x-coordinate of the image is 1

∴ The y-coordinate of the image is 2

∴ C' = (1 , 2)

* The coordinates of triangle A'B'C' are A' (-1 , 1) , B' (2 , 0) , C' (1 , 2)