Euclidean geometry equal (SAS), or two angles and a side equal (ASA) (Book I, propositions 4, 8, and 26). Triangles with three equal angles (AAA) are similar, but not necessarily congruent. Also, triangles with two equal sides and an adjacent angle are not necessarily equal or congruent. The sum of the angles of a triangle is equal to a straight angle (180 degrees). This causes an equilateral triangle to have three interior angles of 60 degrees. Also, it causes every triangle to have at least two acute angles and up to one obtuse or right angle. The celebrated Pythagorean theorem (book I,
Triangle-and-two defense Triangle-and-two defense The triangle-and-two defense is a particular type of defense used in basketball. The triangle-and-two defense is a hybrid between a man-to-man defense in which each defensive player is responsible for marking a player on the other team, and a zone defense in which each defensive player is responsible for guarding an area of the court. In a triangle-and-two defense, three players play zone defense, and align themselves in a triangle protecting the basket, with typically the power forward and center playing directly under the basket, and the small forward playing towards the foul line. The shooting guard and