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How to find area, perimeter

How to find area, perimeter

In order to find an area or perimeter, do not necessarily have great knowledge of geometry.

There are ways to do it without calculation, but the methods requiring knowledge of formulas and the ability to use them, the most accurate.



If you have any figure of the square, forwhich is necessary to determine the area and perimeter, and you can not use the usual formula for the calculation, since it is not a rectangle, a circle or a trapezium, but something more complex configuration, first of all, divide this figure into parts. Typically, the polygons are divided into triangles, if your preset shapes have curved lines in the perimeter, highlight triangle and circle segments. Dostroyte segments to a full circle to be able to measure the desired value.
Dividing all the figures on such items,count for each area. Area of ​​a triangle is equal to half of the Product of one of its sides to a height lowered to the side. Measure the line to the desired length of each triangle, substitute the values ​​into the formula and calculate the area of ​​each triangle. If you have selected other than triangles as the elements, and the circle segments, consider their area according to the formula? ^ 2 * a / 360-S, where a? a central angle, radius, two of which are interconnected by arc segmentation S? area of ​​a triangle formed by the same radii and straight, which you can straighten the arc, connecting radii.
When you know all the areas of individual elements add them to figure out the area of ​​the desired shape.


To find the perimeter, it is necessary to measure allrectilinear segments in it, and put them together. Then add the resulting number, the calculated arc length. circular arc length is calculated as the product of the radius of the circle in the corner and already referred to above.


You can restrict the minimum payments ifuse other methods to determine the area. So you can use mosaic. Put mosaic on top of the figure, which is defined for the area, count all the units overlying the area desired area, and then multiply that number by a certain unit area of ​​the mosaic.


It requires more tools gravimetric methoddetermining the area. If you have accurate scales, copy the desired area of ​​the image on a sheet of known size, weigh it. Now cut image shapes and measure its weight. When you know the area and the weight of a sheet, as well as part of the weight, you can make and to determine the proportion of the area of ​​this part. It is best to use this method if the paper factory production.


And the easiest way to measure the perimeter,lay across the perimeter line of the thread. It is important that the thread exactly coincided with the perimeter. When the thread snaps, ie make a full circle around the perimeter line, mark a point on it, in which thread comes into contact with the place of the origin. Cut and measure the resulting length of the value of your measurement - this is the perimeter of the figure.

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