Warm-Up 11/3/09 #7 ď‚§ Determine all ways to prove the triangles are congruent.
Warm Up 11/3/09 #7
A. Write the congruence statement. B. Name two pairs of corresponding angles. C. Name two pairs of corresponding sides. A
ยง 4.4 The Isosceles Triangle Theorem (ITT) Objective: Find measures of isosceles triangles.
Recall: Isosceles Triangle
Legs Base Base angles Vertex angle
ITT Base angles of an isosceles triangle are congruent. B
ALWAYS ∠ A ≅ ∠C A
Converse of ITT (still called ITT)
ď‚§ If two angles of a triangle are congruent, the sides opposite those angles are congruent. (AB = BC) B
Corollary’s An equilateral triangle is also equiangular
An equilateral triangle has three 60 º angles.
Another Corollary: The bisector of the vertex angle of an isosceles triangle is perpendicular to the base at its midpoint. B
Angle B is bisected by segment BM M is the midpoint of segment AC
Proof! Given: ∠1 ≅ ∠2 Prove: OK = OJ
O 4 K 2
Examples… Find the values of x for each… a)
B) ∠X ≅ ∠Y
2x - 4 Z 2x + 2 x+ 5 Y
Last oneâ€Ś C)
Homework Page 137 1-8, 13, 14 ALL OR NOTHING!