Chapter 2: Q3. (page 62)
a. In each exercise use the information given to conclude that two angles are congruent.
b. Name or state the definition or theorem that justifies your conclusion.
Short Answer
a. From the given diagram it can be concluded that angles∠8and∠9are adjacent angles.
The theorem of perpendicular lines states that if two lines are perpendicular then the lines form adjacent congruent angles.
Like the lines, ABand CDare perpendicular lines and the angles∠8 and∠9are adjacent angles, therefore the angles∠8 and∠9will be congruent angles.
That implies, .
b. The name of the theorem that justifies the conclusion is thetheorem of perpendicular lines.