4.3 ISOSCELES AND EQUILATERAL TRIANGLES
VOCABULARY Two angles of an isosceles triangle are always congruent. These are the angles opposite the congruent sides
BASE ANGLES THEOREM If two sides of a triangle are congruent, then the angles opposite them are congruent
EXAMPLE 1 Use the Base Angles Theorem to find the measure of <L
CONVERSE OF BASE ANGLES THEOREM If two angles of a triangle are congruent, then the sides opposite them are congruent.
EXAMPLE 2 Use the converse of the base angles theorem to find the value of x
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EQUILATERAL THEOREM If a triangle is equilateral, then it is equiangular.
EQUIANGULAR THEOREM If a triangle is equiangular, then it is equilateral.
EXAMPLE 3
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