Problem of the Month: January 2022

ACES Math Coach Mr. Dave helped students at Global Arts Plus in Saint Paul measure angles using homemade protractors!

This month in the ACES classroom, 4th and 5th graders were practicing measuring and adding angles during one of our most popular unites, “Technology in Sports”! Can you identify each of the five types of angles? Test your memory and geometry skills with our January problem of the month!

See the figure below. Can you identify one of each of the following types of angles?

1. Straight Angle

2. Acute Angle

3. Right Angle

4. Obtuse Angle

5. Reflex Angle

Hint: multiple answers are possible. Scroll down to see the solution!

Solution

1.Straight Angle
An angle which measures exactly 180° is called a straight angle.

∠EOC

2. Acute Angle
An angle which measures less than 90° is called an acute angle.

∠AOB

∠BOC

∠DOE

3.  Right Angle
An angle which measures exactly 90° is called a right angle.

∠AOC

∠AOE

4. Obtuse Angle
An angle that measures more than 90° and less than 180° is known as an obtuse angle.

∠BOD

∠COD

∠DOA

∠EOB

5. Reflex Angle
An angle which measures greater than 180° and less than 360° is known as a reflex angle.

∠AOD

∠AOE

∠BOE

∠BOA

∠COA

∠COB

∠DOB

∠DOC

∠EOD