A triangle which has two of its sides equal in length.
Try this Drag the orange dots on each vertex to reshape the triangle. Notice it always remains an isosceles triangle, the sides AB and AC always remain equal in length
The word isosceles is pronounced "eye-sos-ell-ease" with the emphasis on the 'sos'. It is any triangle that has two sides the same length.
If all three sides are the same length it is called an equilateral triangle. Obviously all equilateral triangles also have all the properties of an isosceles triangle.