4.2.5 Isosceles and Equilateral Triangles - Practice
1. Identify the true statement. ○ An equilateral triangle has three congruent sides. ○ An equilateral triangle has three angles that measure 90°. ○ An equilateral triangle has three angles that measure 45°. ○ An equilateral triangle does not have any congruent sides.
2. Identify the true statement. ○ If two angles of a triangle are
congruent, then the sides opposite the angles are not congruent. ○ If two angles of a triangle are congruent, then the sides opposite the angles are congruent. ○ If two angles of a triangle are congruent, then all of the sides are congruent. ○ If two angles of a triangle are congruent, then the third angle is congruent.
4. Find the measures of ∠ B and ∠ C .
3. Identify the true statement. Explain why the statement is true. ○ Every isosceles triangle is equilateral. Isosceles triangles have congruent sides, so they are always equilateral. ○ Every isosceles triangle is equiangular. The sides opposite the base angles are congruent, so the triangle is equiangular. ○ Every equilateral triangle is equiangular. Since all pairs of sides are congruent, all pairs of angles must be congruent. ○ Every isosceles triangle is acute. The base angles of an isosceles triangle are congruent, and no triangle can have two obtuse or two right angles. 5. Find the value of b .
6. Find the value of DF given that DE = 9 x + 11 and EF = 4 x + 31.
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