Question

What statement best fills in the last blank of the proof and completes the sentence: " By the substitution property of equality,..."

Answer 1

Answer:

A. $m\angle A=m\angle B$        

Step-by-step explanation:

We have been given that angle A is a right angle and angle B is a right angle. We are asked to choose the correct option that completes the last statement of the proof.

Let us prove that $m\angle A=m\angle B$ step by step.

First blank:

We have been given that $\angle A \text{ And }\angle B\text{ are right angles}.$.

Second blank:  

This means that $m\angle A=90^o$ and $m\angle B=90^o$

Third blank:

By the definition of right angles a right angle is an angle of exactly 90°.

Last blank:  

Substitution property of equality states that if $a=b\text{ and }b=c\text{ then }a=c$

Hence, by the substitution property of equality $m\angle A=m\angle B$.

Therefore, the statement $m\angle A=m\angle B$ completes the last blank of the proof and option A is the correct choice.  

Answer 2

Since, it is given that angle A is a right angle and angle B is a right angle.

We have to prove that $m \angle A = m \angle B$

Now, we have to complete the given statement.

It is given that $\angle A$ and $\angle B$ are right angles. This means that $m \angle A = 90^\circ$ and $m \angle B = 90^\circ$ because of the definition of the right angles. By the substitution property of equality $m \angle A = m \angle B$.