An isosceles triangle has at least two equal sides.

No, it doesnt have at least 2 equal sides. it has exactly 2 equal sides

but

This is one of those “it depends on the textbook author” questions.  

Some texts define an Isosceles triangle as a triangle with exactly two congruent sides. In this case a triangle with three congruent sides may only be classified as an Equilateral triangle, and not as an Isosceles triangle. In this definition Isosceles and Equilateral are mutually exclusive.  

Other texts define an Isosceles triangle as a triangle with at least two congruent sides. In this case a triangle with three congruent sides may be classified as both an isosceles triangle and an equilateral triangle. In this definition Equilateral is a subset of Isosceles.

50.6

step-by-step explanation:

c

step-by-step explanation:

it would be see because your formula is f(x)=6x, so 6 times 1 is 6 and you go on and the best answer is c.