Write the definition as a biconditional statement. A triangle which has two or more congruent sides is an isosceles triangle.
a. If a triangle has two or more congruent sides, then it is isosceles.
b. If a triangle is isosceles, then it has two or more congruent sides.
c. A triangle has two or more congruent sides if and only if it is isosceles.
d. A triangle is isosceles if and only if it has two or more congruent sides.