Congruency in Isosceles and Equilateral Triangles
Explore the properties of isosceles and equilateral triangles, focusing on congruency theorems and angle relationships.
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Congruency in Isosceles and Equilateral Triangles
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Read each question carefully and answer to the best of your ability. Show all your work for full credit.
1. In an isosceles triangle, if the measure of the vertex angle is 50 degrees, what is the measure of each base angle?
50 degrees
65 degrees
80 degrees
130 degrees
2. Which of the following statements is true for an equilateral triangle?
All sides are different lengths.
Only two angles are equal.
All angles measure 60 degrees.
It has no lines of symmetry.
3. In an isosceles triangle, the angles opposite the congruent sides are .
4. An equilateral triangle is also an triangle.
5. If all three sides of a triangle are congruent, then the triangle is .
6. Triangle ABC is an isosceles triangle with AB = AC. If angle B measures 70 degrees, what is the measure of angle A? Explain your reasoning.
7. Draw an equilateral triangle and label its angles and sides to show its properties.
8. All isosceles triangles are equilateral triangles.
True
False
9. If a triangle has three congruent angles, then it is an equilateral triangle.
True
False
Match the term with its definition.
10. Isosceles Triangle
a. A triangle with all three sides congruent.
11. Equilateral Triangle
b. A triangle with at least two sides congruent.
12. Base Angles
c. The angles opposite the congruent sides in an isosceles triangle.