Answer:
B. At least two of the angles are congruent.
Step-by-step explanation:
We are asked to choose the correct option about the angles of an isosceles triangle. Let us see our given choices one by one.
A. All three angles are congruent.
We know that all angles of an equilateral triangle are equal. We know that each equilateral triangle is an isosceles triangle as it three congruent angles.
For a triangle to be an isosceles triangle at least two angles needs to be congruent, therefore, the given statement is not true.
B. At least two of the angles are congruent.
For a triangle to be an isosceles triangle at least two angles needs to be congruent, therefore, the given statement is true.
C. The vertex angle is a right angle.
The vertex angle is not always a right angle as when each base angle of isosceles triangle is 50 degree, then vertex angle will be 80 degrees, therefore, the given statement is not always true.
D. The vertex angle is obtuse.
The vertex angle is not always an obtuse angle as when each base angle of isosceles triangle is 70 degree, then vertex angle will be 40 degrees, therefore, the given statement is not always true.
