Triangle
Calculate area of a triangle.
Triangle Guide
A triangle is one of the basic polygons in geometry, defined by three sides and three interior angles.The sum of interior angles in any triangle always equals 180 degrees. Triangles can be classified in different ways: by side length (equilateral, isosceles, scalene) or by angle measure (acute, right, obtuse).
The area of a triangle is calculated by multiplying the base by the height and dividing by two.The formula P = (a × h) / 2 is the most commonly used in practice. Height is the distance from the opposite vertex to the base, measured at a right angle to the base. In an equilateral triangle, all sides are equal, and height can be calculated as h = (a√3) / 2.
The Pythagorean theorem applies to right triangles.In a right triangle, the sum of the squares of the legs equals the square of the hypotenuse: a² + b² = c². This is one of the most important theorems in geometry, applied in construction, navigation, physics, and many other fields. The legs are the sides adjacent to the right angle, and the hypotenuse is the longest side opposite the right angle.
Types of triangles. An equilateral triangle has three equal sides and three 60-degree angles. An isosceles triangle has two equal sides (legs) and two equal angles at those sides. A scalene triangle has all sides of different lengths. An acute triangle has all angles less than 90 degrees, a right triangle has one angle equal to 90 degrees, and an obtuse triangle has one angle greater than 90 degrees.