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Unformatted text preview: 4-2 Measuring Angles
A) What is the difference between these two?
a. mABC = 25 ABC b. The first one reads as "the measure of ABC = 25 degrees" c. Turn to page 84 and look at the figure d. degree i. The unit of measure is called a degree e. Measure i. the number of degrees in an angle
f. We don't have to use the degree sign when we write the number in our notation because the m takes care of this: mABC is the number of degrees in the angle B) Postulate 11 (The Angle Measurement Postulate) a. To every angle BAC there corresponds a real number between 0 and 180. b. B A mBAC = r C c. Measure i. The number given by the Angle Measurement Postulate C) Postulate 12 (The Angle Construction Postulate) a. Let AB be a ray on the edge of the half plane H. For every number r between 0 and 180 there is exactly one ray AP , with P in H, such that mPAB = r. b. Draw AB on the edge of plane H. Where can P be located? D) Postulate 13 (The Angle Addition Postulate) a. If D is in the interior of BAC , then mBAC = mBAD + mDAC b. Draw BAC and point D. E) Linear Pair a. If AB and AD are opposite rays, and AC is any other ray, then BAC and CAD form a linear pair b. Draw: F) Supplementary angles a. Two angles whose sum is 180. G) The Supplement Postulate a. If two angles form a linear pair, then they are supplementary ...
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This note was uploaded on 05/16/2011 for the course ALGEBRA 098 taught by Professor Johnson during the Spring '09 term at Grand Valley State University.
- Spring '09