How to draw a 120° angle?
Without the help of a protractor.
It is important to practice this process, to solve various Geometric construction problems, in secondary level school Mathematics.
In this video, we will see all the procedures, with the help of a 3d animation.
First of all, with a scale and a pencil, a line segment is drawn on the middle of the page.
The two endpoints are named, O, and, A.
Next, a pencil compass is taken. A large circle arc is drawn, with the tip of the compass placed at the point, O. The arc of the circle intersects the straight line, O, A, at point, X.
Then, another circle arc, of the same radius, is drawn, with the tip of the compass placed at point X. It intersects the previous arc at point Y.
After that, put the tip of the compass at point Y. And draw another circle arc of same radius, to get an intersection, against the first circle arc. This point of intersection is, named as, Z.
Now, align the rular about the point, O, and the point, Z. And draw a line segment between them. This line segment is named, O, B.
Thus, the angle, AOB is a 120° angle.
Is it 120°, or, not?
Let's verify, with the help of a protractor.
Regular exercise, better Geometrical instruments, can bring the perfection.
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