Pre-Test
Geometry Lesson 1
Introduction to Geometry
Pre-Test |
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| Q&A |
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Instruction 1-2 Definitions | Measuring Angles | Line and Angle Relationships | Triangles | Definitions of Figures |
| MEASURING ANGLESa http://www.cimt.plymouth.ac.uk/projects/mepres/book7/bk7i5/bk7_5i2.htm http://www.mathopenref.com/constmeasureangle.html |
Let's rotate one side of an angle so that it overlaps the other side. The
magnitude of the rotation is called the measure of the angle. The measure
of an angle, say angle A, is denoted by m A. A protractor is a common tool for measuring angles (Figure 1.9).
An angle is measured in degrees. If we divide any circle into 360 equal parts, each part is called a degree. A degree can be divided into smaller units: each degree is is divided into 60 equal pieces called minutes and each minute is divided into 60 equal pieces called seconds. So we can say that a degree is equal to (60 times 60)=3,600 seconds. Degree units are denoted by ˚, minutes by ‘, and seconds by “. For example, 32 degrees, 37 minutes, and 76 seconds is denoted by 32˚ 37’ 76”. Most of the angles you measure with a protractor will only be measured in degrees, not minutes or seconds.
Now let's do Practice Exercises 1-2 (top).
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