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,
Hyperbolic triangle In other words, the quantity in the paragraph above is supposed to be equal to 1. Trigonometric formulas for hyperbolic triangles depend on the hyperbolic functions sinh, cosh, and tanh. If "C" is a right angle then: We also have the following equations: The area of a right angled triangle is: also The instance of an omega triangle with a right angle provides the configuration to examine the angle of parallelism in the triangle. In this case angle "B" = 0, a = c = formula_18 and formula_19, resulting in formula_20. The trigonometry formulas of right triangles also give the