Check the picture below.
bear in mind that, if the right-triangle is an isosceles, is a 45-45-90 triangle, and if we split it from the "vertex" above perpendicular to the base, we end up with two more 45-45-90 triangles.
bear in mind that, if the right-triangle is an isosceles, is a 45-45-90 triangle, and if we split it from the "vertex" above perpendicular to the base, we end up with two more 45-45-90 triangles.