Question

The vertices of a triangle are, A (2, 5) B (1, 2) C (3, 1),. Find the coordinates of the image after a

reflection in the x-axis, and then a rotation 90° counterclockwise about the origin.

Answer 1

A’ (5,2) B’ (2,1) and C’ (1,3)

Step-by-step explanation:

Firstly, we want to reflect across the x-axis

When we reflect a point (x,y) over x-axis, we get (x,-y)

So;

A ( 2,5) becomes (2,-5)

B (1,2) becomes (1,-2)

C ( 3,1) becomes (3,-1)

Then we proceed to rotate 90 degrees counterclockwise about the origin

Here we have;

(x,y) becomes (-y,x)

(2,-5) becomes (5,2)

(1,-2) becomes (2,1)

(3,-1) becomes (1,3)

Answer 2

The images are;

A’ (5,2) B’ (2,1) and C’ (1,3)

Explanation:

Firstly, we want to reflect across the x-axis

When we reflect a point (x,y) over x-axis, we get (x,-y)

So;

A ( 2,5) becomes (2,-5)

B (1,2) becomes (1,-2)

C ( 3,1) becomes (3,-1)

Then we proceed to rotate 90 degrees counterclockwise about the origin

Here we have;

(x,y) becomes (-y,x)

(2,-5) becomes (5,2)

(1,-2) becomes (2,1)

(3,-1) becomes (1,3)