What is an angle? An angle is often defined as a figure where two rays share a common endpoint (vertex). In elementary school you learn about acute, obtuse, and right angles. In middle school, we go further with the development of angles and you'll see just how totally cool these things really are!

protractor: tool used to measure angles. Angles are measured in degrees.

The angle is the 'opening' or arc. (Note: If you need a protractor, click download protractor.)

right angle: an angle that measures exactly 90°. A little square that connects the two 'legs' of the angle indicate that an angle measures exactly 90°.

acute angle: an angle that measures less than 90°. An arc connects the two 'legs' to indicate the measure of the angle.

obtuse angle: an angle that measures greater than 90° but less than 180°. An arc connects the two 'legs' to indicate the measure of the angle.

vertex: a point where two rays meet in an angle

ray: a part of a line that has an endpoint and continues in one direction

Now, we're going to take the vocabulary you already know and add to it. Then, using logical thinking skills, we'll see what you math problems you can figure out simply from 'knowing the math.'

Moving on, let's go to some more angles, shall we? Next page…