Question

name each angle in four ways. 19) 20) 21) 22)

Explanation:

Step1: Use vertex - centered naming

The vertex of the angle is the key point. For an angle, we can name it using the vertex alone (if there is only one angle at that vertex), or by using three points with the vertex in the middle, or by using a number or a letter assigned to the angle.

Step2: Name angle in figure 19

• By vertex: $\angle C$
• By three - points: $\angle BCD$ or $\angle DCB$
• By number: $\angle 5$
• If we assign a letter, say $\angle \alpha$

Step3: Name angle in figure 20

• By vertex: $\angle F$
• By three - points: $\angle EFG$ or $\angle GFE$
• By number: $\angle 5$
• If we assign a letter, say $\angle \beta$

Step4: Name angle in figure 21

• By vertex: $\angle K$
• By three - points: $\angle JKL$ or $\angle LKJ$
• By number: $\angle 5$
• If we assign a letter, say $\angle \gamma$

Step5: Name angle in figure 22

• By vertex: $\angle K$
• By three - points: $\angle JKL$ or $\angle LKJ$
• By number: $\angle 5$
• If we assign a letter, say $\angle \delta$

Answer:

For figure 19: $\angle C$, $\angle BCD$, $\angle DCB$, $\angle 5$
For figure 20: $\angle F$, $\angle EFG$, $\angle GFE$, $\angle 5$
For figure 21: $\angle K$, $\angle JKL$, $\angle LKJ$, $\angle 5$
For figure 22: $\angle K$, $\angle JKL$, $\angle LKJ$, $\angle 5$