WHAT'S YOUR ANGLE?

• Did you know that when you measure an angle, the number ofdegrees you measure tells what part of a circle the angle is? That’s right.Every angle is a part of a circle. A circle is divided up into 360 tiny littleslices, called degrees. The word “degrees” can alsobereplaced bythis mathematical symbol: º, usually written slightly up to the right just after the number in a measurement. When you measure an angle, you are basically counting how many of the circle’s 360 degrees fit in the spacebetween the two armsof your angle.

• A straight angle is when the two arms of the angle lay flat in a straight line. A straight angle measures 180º.  A right angle forms a perfectly square corner, with one arm of the angle laying flat on the straight line, and the other arm pointing straight up. A right angle measures exactly 90º. An angle that has less than 90º is called an acute angle. Some people remember the name of the acute angles by thinking about them being the smallest of the angles, and things that are tiny are often cute. “What a cute little angle!”  An angle that has more than 90º is called an obtuse angle.

• While it is possible to estimate the approximate size of an angle just by looking at it, sometimes other tools are necessary. In the case of a right  angle, a special symbol lets you know at a quick glance that it measures  exactly 90º. Just look for a small square in the corner formed by the two arms of the angle. For all other angles, though, you may want to take out either a protractor or an angle ruler. Both have markings that show the360 degrees of a circle so that you can line them up with the arms of the angle you want to measure, and find out precisely how much of the circle fits between the two arms of the angle. Before long, you’ll know exactly what your angle is.

Name:__________________________________

Answer the following questions based on the reading passage. Don’t forget to go back to the passage whenever necessary to find or confirm your answers.

1.  Why do we measure angles in degrees? 
2. Which kind of angle has a special symbol that helps you know its measurement? 
3. What tools can help you find out the precise measurement of an angle?
4.  What is another name for a straight angle? 
5. In your own words, explain the relationship between a circle and an angle.