An isosceles triangle is a triangle with two congruent, or equal, sides. For example, this is an isosceles triangle:
a triangle with two sides marked congruent
And although this triangle points a different way, it's also an isosceles triangle:
Two equal sides make an isosceles triangle.
a triangle with two sides marked congruent
No matter which direction the triangle's apex, or peak, points, it's an isosceles triangle if two of its sides are congruent.
Note the hash marks that indicate congruency. Any