The area of a geometrical figure depends on lengths of its parties, and in certain cases - as well on corners between them. There are ready formulas for determination of the area of a rectangle, a square, a circle, the sector, a parallelogram, an ellipse and other figures.
Instruction
1. To calculate the area of a rectangle, increase at each other lengths of its two parties adjoining to each other. At a square all parties are equal among themselves therefore for calculation of its area it is necessary to square length of any of its parties.
2. For determination of the area of a circle square its radius, and then increase by number π. If it is not about all, and about its sector, divide result of the previous calculation into 360, and then increase by the sector corner expressed in degrees. In case this corner is expressed instead of degrees in radians, instead of number 360 use number π. It makes (to within the tenth sign after a comma) 3.1415926535 and is dimensionless size.
3. You find the area of a rectangular triangle as follows: increase at each other lengths of legs then increase result by 0.5 (or that the same, divide into 2). At an equilateral triangle the area is equal to the square of any of the parties increased by a square root from number 3 and divided into 4. Any other triangle can be presented conditionally in the form of two rectangular, having carried out in it height. Having carried out this operation in the graphic way, height and also it is possible then to measure the turned-out legs of rectangular triangles. If higher precision is required, in the beginning find poluperimetr a triangle, having put lengths of all its parties and having divided result into two. Then use the following formula: S=sqrt (p(p-a) (p-b) (p-c)) where S is the area, p - poluperimetr, a, b, c - the parties. If it is known one parties of a triangle and two corners, adjacent to it, use other formula: S=(c^2*sinα*sinβ) / (2sin(α+β)) where S is the area, with - the party, α and β - corners.
4. The parallelogram represents a figure which can be divided into a rectangle and two identical rectangular triangles conditionally. If the accuracy of a graphic way of measurement of the parties of the turned-out figures does not suit you, and the acute angle of a figure is known, use the formula shown below: S=a*b*sinα where S is the area, a, b are the parties, α - an acute angle of a parallelogram.
5. The ellipse, unlike a circle, has two radiuses - bigger and smaller. Both of them are called half shafts. To calculate the area of an ellipse, increase lengths of its half shafts at each other, and then by number π.