# Rotations Exploration 1 - 90° (Teacher Copy)

## Work with the teacher.

**a**. Draw a triangle with vertices at

*A*(1,3)

*B*(4,3), and

*C*(4, 1).

**b**. Create a point at the origin

*D*(0,0).

**c**.

*Rotate*the triangle 90° counterclockwise about the origin to form triangle

*A*'

*B*'

*C*'.

**d. **What is the relationship between the coordinates of the vertices of triangle *ABC* and those of triangle *A'B'C'? *Write a rule to determine the coordinates of the image of (*x*, *y*).

**e.** Find the side lengths and angle measures of the two triangles. What do you notice?