By definition, there is no such thing as a triangle with 100 sides. A triangle has exactly three (straight) sides; no more and no less.
Having three sides means that the shape also has three internal angles and this explains the name.
Ummm... A triangle has 3 sides.
The name for a triangle with two sides of equal length is an isosceles triangle.
If all of its sides are the same length its an equilateral triangle. If only two of its sides are the same length it is an isosceles triangle. If all the sides are different lengths it is a scalene triangle
a scalene triangle has no equal sides. an isosceles triangle has two equal sides
A scalene triangle
a scalene triangle
Equilateral triangle
A scalene triangle
an isosceles triangle
An isosceles triangle has two congruent sides.
Isoseles triangle has two equal sides.
Every triangle has three sides. If it has any number of sides other than three, then it isn't a triangle.