The construction of copying ∠"QPR" is started below. The next step is to set the width of the compass to the length of ("AB" ). How does this step ensure that the new angle will be congruent to the original angle?

Constant radius, AB = TU

Step-by-step explanation:

Construction: Copying of <QPR, so that;

         <QPR = <TSU

The compass is placed in such a way that its two pointed legs are place at points A and B respectively to copy distance AB.

Now, place the compass at T and describe an arc to locate point U. Draw a straight line through S and U.

Therefore,

             <QPR = <TSU

The step ensures that the angles are congruent by constant radius, AB = TU.