To draw a right angle it seems simple if near at hand there are technical devices. And if is not present? Or you need to construct a right angle in the big square, for example, a ground. And how many exists ways to construct a right angle?

## It is required to you

- - ruler;
- - drawing triangle;
- - pencil;
- - compasses;
- - rope;
- - cargo.

## Instruction

1. Way first – by means of a ruler, a pencil and a protractor. Draw a straight line by means of a ruler. Note on it a point. Combine a point with the middle of a protractor. Find mark 90o in a protractor scale and designate it by a point. Draw a line through two points. Two straight lines are crossed with each other at right angle.

2. Way second – by means of a ruler triangle and a pencil. One corner at a straight line triangle. Apply it one party to the line from which it is necessary to construct a right angle. On the perpendicular party of a triangle from the line draw a piece. The angle between a piece and the line will be right. Or just circle a right angle of a triangle with a pencil on paper.

3. Way third – by means of a rectangular subject. As well as a drawing triangle, you can use any subject which corners direct. For example, book, folder, box.

4. Way fourth – by means of a ruler and a pencil. From a point And postpone two pieces of AV and the EXPERT of one length at an acute angle to each other. Connect their ends – at you the isosceles triangle will turn out. Find the middle of its basis of D and connect to A top. The piece of AD is a median, a bisector, height, i.e. is perpendicular to VS basis.

5. Way fifth – by means of a ruler, a pencil and compasses. In geometry the entered corner relying on diameter – a straight line. Draw compasses a circle. Carry out diameter through its center. Note any point on a circle and connect it to the ends of diameter pieces. The corner formed by pieces – a straight line.

6. Way sixth is other option of creation of a right angle by means of compasses and a ruler. Draw two any circles so that they were crossed with each other in two points. Connect these points RR piece’. Then draw a straight line through the centers of circles. The piece and a straight line are crossed at an angle 90 lakes.

7. Way seventh – if you have to construct a perpendicular on a vertical surface, for example a wall, use a plumb. Tie cargo to one end of a rope. Now, if you hold for other end, the rope will be tense at an angle 90o to a horizontal. Having brought closer a plumb to a wall, draw a straight line along a rope. The angle between the line and a floor will be right if the gender of you is horizontal.

8. Way eighth – by means of a rope with the small knots tied through 12 equal intervals and Pythagorean theorems. This method was used by ancient Egyptians. If to pull this rope so that it formed a triangle with the parties in 3, 4 and 5 intervals, the angle opposite to the long party will be right. On Pythagorean theorem: 3^2+4^2 = 5^2. Means, a triangle – rectangular.