Geometry Chapter 1 Part 5

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Continued Building Blocks and Defined Terms Table 1.2 Term Definition Illustration 'Angle' " An 'angle' is the union of two (connect the ^ rays having the same end point. arrows and place J / The end point is called the the dots to the / 'vertex' of the angle, and the rays letters) K / are called the 'sides' of the angle. / ____L__> 'Vertex': K _____> _____> (For the impaired- these 'Sides' have arrowed lines over them) KJ and KL "Naming Angles An angle may be named in one of three ways: 1. Using three letters, the center letter corresponding to the vertex of the angle and the other letters representing points on the sides of the angle" For example. in a figure 1.2 of an angle with the 'vertex' of T the angle is RTB (___RTB) or angle BTR (___ BTR) 2. "Placing a number at the 'vertex' and in the 'Interior' which is the inside of the angle. The angle may then be referred to by the number. "In the case of an angle RTB with an angle at T named 1, it can be said to be ___1. It can also be represented by ___ RTB or ___BTR. The space outside of the angle next to each side TR and TB are considered the 'Exterior' of the angle. 3. "Using a single letter that corresponds to the vertex" of an angle on a plane with a "A" at one corner which we consider to be the vertex of that angle but considering there is also "B", "C", and "D" angles also. Then there is a line through the middle connecting "B" and "D" making those Two different 'vertex' for the plane which makes sense to use numbers in place because The A angle can be ___A or __1, the one angle __B can be ABC __2, or divided DBC__3 and ABD __4, angle C be DCB__5 for one big angle at D of ADC __6, or divided as ADB ___7 and BDC of___8. In order to uniquely identify the angle having D as its vertex we must either name the angle with three letters or introduce a number into the diagram. (Continue next lesson)