Geometry Lesson 1 By Lorraine Gordon Olde Towne Middle School 3a: Locate and Identify angles formed by parallel lines cut by a transversal (e.g., adjacent, vertical, complementary, supplementary, corresponding, alternate interior, and alternate exterior).
Transversal A line that intersects two other lines in different points is a transversal Line N is a Transversal
Transversal Transversals form 8 angles by bisecting (cutting across) two different lines. The two lines this transversal is bisecting are parallel. The angles that are formed are adjacent, vertical, complementary, supplementary, corresponding, alternate interior, and alternate exterior.
Vertical Angles Are formed by two intersecting lines and are opposite each other. Vertical angles are congruent (have the same measurement) Vertical angles form an X. Vertical angles are across from each other or nose to nose <1&<4, <2&<3, <5&<8, <6 &<7 are vertical angles.
Adjacent Angles Adjacent angles share a vertex and a side but no points in their interior. Adjacent angles are side by side or back to back <1&<2, <1&<3, <2&<4, <3&<4, <5&<6, <6&<8, <5&<7, <7&<8 are all adjacent pairs of angles.
Supplementary Angles Two angles that add together to form a 180 degree angle. <a&<b are supplementary because the sum of these two angles equals 180 degrees (forms a straight line)
Complementary Angles The sums of the measures of two angles is 90 degrees. <AOC & <COB add together to make <AOB which is 90 degrees.
Corresponding Angles Lie on the same side of the transversal and in corresponding positions. <EFB &<FGD are corresponding angles. They are also congruent. Name the other corresponding angles.
Alternate Exterior Angles Located on the outside of the parallel lines and on opposite sides. <H & <B and <G & <A are alternate exterior angles. Alternate exterior angles are congruent
Alternate Interior Angles Are in the interior (inside) of a pair of lines and on opposite sides of the transversal. <E & <C and <F & <D are alternate interior angles Alternate interior angles are congruent They form a Z pattern.
Wrap up Name two pairs of adjacent angles. Name a pair of corresponding angles. <1 & <2 are supplementary or complementary? Name a pair of alternate interior angles. Name a pair of alternate exterior angles