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Transcript
Isosceles Triangles Geometry Ms. Reed Unit 4, Day 2 Parts of an Isosceles Triangle Legs Base Parts of an Isosceles Triangle Vertex Angle Base Angles With your Isosceles Triangle: • Measure all three sides and angles • With a partner, discuss your results. • What did you notice? Three Triangle Postulates 4-1: If two sides of a triangle are congruent, then the angles opposite those sides are also congruent. What it looks like: http://www.usna.edu/Users/cs/lmcdowel/courses/ic210/F07/labs/IC210_Lab_3_IsoscelesTriangle.gif How to use it: Find x. http://education.yahoo.com/homework_help/math_help/solutionimages/minigeogt/4/1/1/minigeogt_4_1_1_19_30/f-226-31-ex-1.gif Three Triangle Postulates 4-1: If two sides of a triangle are congruent, then the angles opposite those sides are also congruent. 4-2: The bisector of the vertex angle of an isosceles triangle is the perpendicular bisector of the base. What it looks like: CD is the bisector of ACB. Make the appropriate markings on the triangle using Theorem 4-2. How to use it: Find the perimeter and area of the triangle. Three Triangle Postulates 4-1: If two sides of a triangle are congruent, then the angles opposite those sides are also congruent. 4-2: The bisector of the vertex angle of an isosceles triangle is the perpendicular bisector of the base. 4-3: If two angles of a triangle are congruent, then the sides opposite the angles are congruent. What is looks like: How to use it: • A B, BC = 5. Find AC. C 5 A B Practice • Find the values of x and y. Homework Work Packet: Isosceles Triangles