https://doi.org/10.4169/college.math.j.47.5.356 https://www.jstor.org/stable/10.4169/college.math.j.47.5.356 This paper provides a new, long proof of the Pythagorean ...

The three angles in a triangle add up to \(180^\circ\). If two of the angles are known then the third can be calculated by following these steps: Add the two known angles together. Subtract the total ...

American Journal of Mathematics, Vol. 39, No. 1 (Jan., 1917), pp. 41-58 (18 pages) ...

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. What is a triangle? We all know that a triangle is a three-sided shape — 1, 2, 3 sides. A triangle also ...