Question

Name the definition or state the theorem that justifies the statement about the diagram.

If $\angle ABD$and $\angle DBE$are complementary angles, then $m\angle ABD+m\angle DBE=90$.

Short answer

The used definition is the definition of perpendicular lines.

Step-by-step solution

Step 1. Observe the given statement and figure.

The provided equation is the result of the given property of the angles.

Step 2. Identify the definition or theorem.

The observation of statement returns the definition of perpendicular lines that is the relation between two lines is perpendicular when the measurement of angles formed by those lines is equal to 90°.

Step 3. State whether the definition is true or not.

As the definition of perpendicular line matches with the provided statement so the definition of perpendicular lines is the required definition.