Many types of triangles are known: correct, isosceles, acute-angled and so on. All of them have properties, characteristic only of them, and at everyone the rules of finding of sizes, be it the party or a corner at the basis. But from all variety of these geometrical figures in separate group it is possible to allocate a triangle with a right angle.
It is required to you
- Blank sheet, pencil and ruler for the schematic image of a triangle.
Instruction
1. The triangle is called rectangular if one of its corners is equal 90 degrees. It consists of two legs and a hypotenuse. A hypotenuse call the greater side of this triangle. It lies against a right angle. Legs, respectively, call its smaller parties. They can be as are equal among themselves, and to have different size. Equality of legs means that you work with an isosceles rectangular triangle. Its charm that it unites in itself(himself) properties of two figures: rectangular and isosceles triangle. If legs are not equal, then the triangle any and submits to the basic law: the more the corner, the more lying opposite to it rolls.
2. There are several ways of finding of a hypotenuse on a leg and a corner. But before using one of them, it is necessary to define what leg and a corner are known. If the corner and a leg, adjacent to it, is given, then everything is easier to find a hypotenuse on a cosine of the angle. A cosine of an acute angle (cos a) in a rectangular triangle call the relation of an adjacent leg to a hypotenuse. From here follows that a hypotenuse (c) it will be equal to the relation of an adjacent leg (b) to a cosine of the angle of a (cos a). It can be written down so: cos a=b/c => c=b/cos a.
3. If the corner and an opposite leg is given, then it is necessary to work with a sine. The sine of an acute angle (sin a) in a rectangular triangle is the relation of an opposite leg (a) to a hypotenuse (c). Here the principle, as in the previous example works, only instead of function of a cosine the sine undertakes. sin a=a/c => c=a/sin a.
4. It is also possible to use such trigonometrical function as a tangent. But finding of required size slightly will become complicated. A tangent of an acute angle (tg a) in a rectangular triangle call the relation of an opposite leg (a) to adjacent (b). Having found both legs, apply Pythagorean theorem (the square of a hypotenuse is equal to the sum of squares of legs) and the greater side of a triangle will be found.