Question

explore the properties of rotation by following these steps.

1. press rotate to perform a rotation of △abc about point p.
2. make a conjecture: what do you think is the measure of the angle of rotation? 90°
3. the diagram shows two corresponding vertices connected to the center of rotation. use the protractor to measure it. m∠apa = □°

Explanation:

Step1: Observe the rotation

The triangle $\triangle ABC$ is rotated about point $P$ to get $\triangle A'B'C'$. We are asked to measure the angle between a vertex and its corresponding vertex with respect to the center of rotation.

Step2: Use the protractor

By aligning the protractor with point $P$ such that one side of $\angle APA'$ is on the 0 - degree mark of the protractor, we can read the measurement of the angle. Since the conjecture in step 2 was that the angle of rotation is $90^{\circ}$, and the angle between a point and its rotated - image point about the center of rotation is equal to the angle of rotation.

Answer:

$90$