lesson 4-5: isosceles & equilateral triangles vocab legs base angles equiangular bisects the...
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Lesson 4-5: Isosceles & Equilateral Triangles
VocabLegs
Base Angles
Equiangular
Bisects
The congruent sides of an isosceles ∆
Congruent angles opposite the legs of an isosceles ∆
A triangle with all three angles congruent (all 600) – also equilateral
Cuts into 2 equal pieces
Isosceles Triangle
leg leg
base
base angles
•Legs are congruent
•Base angles are congruent
•If we know 1 angle, we can find the rest
Always start byidentifying baseangles and legs!
If one is true, the other must be true!
Answer: A
Multiple-Choice Test Item If and what is the measure of
A. 25 B. 35 C. 50 D. 130
Mark given information first
Identify legs & base angles
Use angle relationships
Equilateral Triangles
•A special type of isosceles triangle
•All sides and angles are congruent
•Also called equiangular
•All angles must be 600
a. Find x.
b.
Answer: 90
Answer: 30
ABC is an equilateral triangle. bisects
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