What does understand and plan and solve and check mean

Are the corresponding angles congruent? explain why or why not.

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 a new angle will be congruent to the original angle? by using compass take the measures of angle and draw the same arc according to it.

Give another definition of variability and explain how it can be calculated.