By definition from geometry, a triangle is called the figure consisting of three tops and three pieces which are in pairs connecting them. There is a large number of formulas for calculation of the area of triangles, for each type of triangles it is possible to use a special formula.
Instruction
1. The area of any triangle can be counted, knowing lengths of its parties on a formula of Heron: S = √ (p * (p - a) * (p - b) * (p - c)), where a, b, c – the parties of a triangle, p = (a + b + c)/2 – poluperimetr.
2. The area of a rectangular triangle can be calculated in several ways: 1. On two legs of S = a * b/2, a, b are legs, 2. On a leg and opposite to it to S corner = a²/2tg ∠α,3. On a leg and adjacent to it to S corner = (a² * tg β)/2.4. On a leg and a hypotenuse of S = a * √ (with² - a²)/2, where with – a hypotenuse, an – a leg, 5. On a hypotenuse and adjacent to it uglams = (with² * sin ∠α * cos α)/2 or S = (with² * sin ∠α * sin β)/2
3. For formules = (a² * √3)/4 where an is the party of a triangle
4. If in any triangle there is one known party and two corners, adjacent to it, then its area is calculated on formulams = with² / (2 * (ctg ∠α * ctg ∠β)) or S = (with² * sin ∠α * sin β)/2 * sin (∠ α + ∠ β)