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Geometry Formulas

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Updated 2008-05-29 00:18

Triangles

Question Answer
three interior angles =180 degrees
exterior anglesthe adjacent angle which is formed by extending one side of the triangle
remote interior anglesthe two non-agjacent angles opposite the exterior angle
relationship of exterior angles to the remote interior anglesexterior angles = sum of remote
relationship of side legnth to the angle sizelongest side opposite longest angle; shortest angle opposite shortest angle
triangle inequalitythe sum of the legnths of a triangle must be greater than the legnth of the third side
base angles of an isoscelesin an isocales triangle base angles are equal in measure
midsegmentthe segment joining the midpoints of two sides of a triangle
triangle midsegment relationsmidsegment of a triangle is parallel to the third side of a triangle; a triangle midsegment is one-half the length of the third side
congruenceall sides are equal in length and all corresponding angles are equal in measure = + ~
congruent trianglesSSS, SAS, ASA, AAS
(SSS)three sides of a triangle are congruent to three corresponding sides of a triangle
(SAS)two sides of a triangle and the angle included between the two sides are congruent to two corresponding sides and the included angle of another triangle
(ASA)two angles of a triangle and the side included between the two angles are congruent to two corresponding angles and the included side of another triangle
(AAS)the two angles of a triangle and the side not included between the two angles are congruent to two corresponding angles and the non-included side of another triangle
(AAA)not a congruence pattern
(SSA)not a congruence pattern
CPCTCcorresponding parts of congruent triangles are congruent; the definition of congruence
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