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Isosceles Triangles. Sec: 4.6 Sol: G.5. 3. Leg. Leg. 1. 2. Base. Properties of Isosceles Triangles. An isosceles triangle is a triangle with two congruent sides. The congruent sides are called legs and the third side is called the base. Vertex. Base Angles. A. B. C.
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Isosceles Triangles Sec: 4.6 Sol: G.5
3 Leg Leg 1 2 Base Properties of Isosceles Triangles An isosceles triangle is a triangle with two congruent sides. The congruent sides are called legs and the third side is called the base. Vertex Base Angles
A B C Theorem 4.9 Isosceles Triangle Theorem If two sides of a triangle are congruent, then the angles opposite those sides (base angles) are congruent.
Find the measure of the missing angle If What is the measure of
A B C A 3x - 7 x+15 ° ° B 50 50 C Theorem 4.10 If two angles of a triangle are congruent, then the sides opposite those angles are congruent. Example: Find the value of x. Since two angles are congruent, the sides opposite these angles must be congruent. 3x – 7 = x + 15 2x = 22 X = 11 Lesson 3-2: Isosceles Triangle
Example: • Name Two Congruent Angles: • Name Two Congruent Segments:
Properties of Equilateral Triangles Corollaries: 4.3 A triangle is equilateral if and only if it is equiangular. 4.4 Each angle of an equilateral triangle measures 60°. 60° 60° 60°
Example: Triangle EFG is equilateral, and segment EH bisects angle E Find the measure of angle 1 and 2: Solve for X:
Assignments: Classwork: WB pg 51 1-6 Homework: Worksheet 4-6