**TI83F* AppVariable file 12/24/08, 18:38\ KGLGE05KInav 9AE51D1EC13445C5B24A00CF0B737DCFGLGE05.GLGE051  altitude!~altitude:A line segment perpendicular to the base of a figure with endpoints on the base and on the vertex opposite the base. centroidV !ycentroid:The point of intersection of the three medians of a triangle. In the figure, X is the centroid of triangle JKM.  circumcenterTcircumcenter:The point of concurrency of the perpendicular bisectors of a triangle. concurrent linesV !concurrent lines:Three or more lines or segments that meet at a common point. In the figure, seg. JR, seg. KP, and seg. MQ are concurrent. incenterHincenter:The point of concurrency of the angle bisectors of a triangle. indirect proof 2indirect proof:In an indirect proof, one assumes that the statement to be proved is false. One then uses logical reasoning to deduce that a statement contradicts a postulate, theorem, or one of the assumptions. Once a contradiction is obtained, one concludes that the statement assumed false must be true. indirect reasoningindirect reasoning:Reasoning that assumes that the conclusion is false and then shows that this assumption leads to a contradiction of the hypothesis like a postulate, theorem, or corollary.Then, since the assumption has been proved false, the conclusion must be true. median !median:In a triangle, a line segment with endpoints that are a vertex of a triangle and the midpoint of the side opposite the vertex.   orthocenterEorthocenter:The point of concurrency of the altitudes of a triangle.  perpendicular bisector!vperpendicular bisector:A segment that is perpendicular to another segment and passes through that segment's midpoint.  point of concurrencyDpoint of concurrency:The point of intersection of concurrent lines.  proof by contradictionGproof by contradiction:An indirect proof in which one assumes that the statement to be proved is false. One then uses logical reasoning to deduce a statement that contradicts a postulate, theorem, or one of the assumptions. Once a contradiction isobtained, one concludes that the statement assumed false must in fact be true.8`0HxHH ( ɍ&PI)*`9I)*@8@06QP@0 @@   @@ @0 @@@       8$$$88`0HHH0|p |@`~` 0 ? b!0A )A 0 (0 P`8`0HxHK?@@ @0    0 0 0  0" 0  9` )ecbVU("dU(,CRbT"@A`  M% %@(͙ @@@00 ? @    @$ @8 4Pab @ &aUJP@ %AULP @51TeXb9