13-1 Angles

TIPS: 

Remember that an acute angle is "a cute little angle" less than 90 degrees. 

Right angles measure 90 degrees, like a corner. Here's a joke about right angles - Saw a right angle resting under a tree this afternoon and thought....  Wow! 90 degrees in the shade!!

An obtuse angle is a larger than 90 degrees. The word obtuse starts with the letter “O” (for obtuse ) comes after the letter “A” (for acute), and 180 comes after 90. Therefore, you can remember that an obtuse angle is larger than an acute angle by remembering that the letter “O” comes after the letter “A” in the alphabet just like how you get taller/bigger later in your life.  

A straight angle is just a straight line. It measures 180 degrees.

A reflex angle is more than 180 degrees but less than 360.  If you draw a straight line and then take one end and move it up or down, you'll find that you have made two angles. The largest of these is the reflex angle. 

A full circle measures 360 degrees. 

To sum up:

There are six types of angle in total;

An Acute angle is the smallest, measuring more than 0° but less than 90°.

Next up is a Right angle, also taught as a quarter turn. This angle always measures 90 °.

An Obtuse angle measures more than 90° but less than 180°.

A Straight angle or a half turn is always 180 °.

Reflex is the next largest measuring more than 180° but less than 360°.

We then have a full rotation or full circle at 360°.