Question

Use the image to determine the direction and angle of rotation.

graph of triangle ABC in quadrant 4 and a second polygon A prime B prime C prime in quadrant 1

270° counterclockwise rotation
180° clockwise rotation
90° counterclockwise rotation
90° clockwise rotation

Answer 1

90° counterclockwise

Explanation:

Find the center of rotation. This is the point that is equidistant from each vertex and its image. You can do this by drawing the perpendicular bisectors of the segments that connect each vertex and its image, and finding their intersection point. In this case, the center of rotation is the origin (0,0).

Choose a vertex and its image to measure the angle of rotation. For example, you can use A and A’. Draw a line segment from the center of rotation to each point, forming an angle.

Use a protractor or estimate the angle of rotation by comparing it to benchmark angles. In this case, the angle of rotation is about 90 degrees.

Determine the direction of rotation by observing which way the figure moved around the center of rotation. In this case, the direction of rotation is counterclockwise (positive).