A special right triangle is a right triangle with some regular feature that makes calculations on the triangle easier, or for which simple formulas exist.
Angle based right triangle: 306090, 454590. (Angles that form a simple ratio)
Side based right triangle: 345 (The lengths of the sides form a whole number ratio),
approx angles 3753.
Knowing the ratios of the angles or sides of these special right triangles allows one to quickly calculate various lengths in geometric problems without resorting to more advanced methods.
