An acute angle is less than 90°. An obtuse angle is between 90° and 180°. A reflex angle is between 180° and 360°. The size of an angle can be estimated without using a protractor.

Learn how to draw and measure angles with this BBC Bitesize Maths article. For students between the ages of 11 and 14.

Electronic enthusiasts that need to measure angles on their robotic arm or other projects may be interested in a new proximity sensor that has been created by William Moore called the Protractor.

Actually, you would have to take your angle measurement and subtract from 90° to get your latitude. Also, there is a straw on top of my protractor to assist with the aiming—and it looks cool.