A triangle which has two sides of the same length is known as isosceles triangle. It has two equal sides and two equal angles. The word is derived from the Greek word 'iso' (meaning 'same') and skelos (meaning 'leg'). An equilateral triangle (a triangle having all three sides as equal) can be an isosceles triangle but not every isosceles triangle is an equilateral triangle. There is a special kind of isosceles triangle known as 'isosceles right triangle.' It is a right-angled triangle with two sides and two corresponding angles as equal. Thus an isosceles right triangle has angles of 45, 45 and 90 degrees.
