Circle Drawing
Construction of a figure is very important in geometry. Before you draw any figure or shape, such as a circle, you have to know about its basic properties. The construction of different geometrical figures is possible with the help of instruments such as a scale, compass, and a protractor. You know that when drawing, you always use a pencil. Here, we will learn how to draw a circle with the help of geometrical instruments.
It is essential to know that to draw a circle; you need to have certain measurements. The measurements may be about the radius or the diameter. As we go further, we shall learn about the radius and the diameter of a circle and how they help in drawing a circle.
Draw the Circle
In other words, to draw a circle, we should have the measurements of a given radius or the diameter. These terms define the properties of a circle. Before we start with the construction of a circle, let us discuss the properties of a circle that will help us in drawing the perfect circle.
The properties of a circle are as follows:
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Every circle has a radius and a diameter.
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The diameter is any straight line segment passing through the centre of the circle.
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The diameter joins two opposite points lying on the circumference or boundary of the circle.
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The radius of a circle is a straight line or segment that joins the centre of the circle to any point on the circumference or ring of the circle.
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The length of the radius is always half of its diameter. Ref Fig.2
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Every point on the ring or circumference of a circle is equidistant from the centre.
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How to Draw a Perfect Circle
We can draw a circle whose radius is given. For the construction of a circle, we need a ruler and a compass. We have to draw a circle with a given radius of 5 cm. Let us start with the following steps.
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Place the pointer of the compass at the point 0 cm of a ruler.
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Extend the other arm with the pencil to measure 5 cm.
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Mark a point O with the pointer on a page of your book. This is the centre of the circle.
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Turn the extended pencil-arm of the compass through 360 degrees to draw a full circle.
Points to Remember:
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Move the compass in one stroke to reach the point from where you start drawing. Ref Fig 3a.
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Hold the pointer of the compass stable so that you get a neat circle. Fig 3b
(images will be uploaded soon)
Radius, Diameter, Chord, and Circumference of a Circle
You know now that to draw a circle, it is essential to know the following parts of a circle
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Radius
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Diameter
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Chord
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Circumference
The distance between the midpoints and the circumference of the circle is the radius. A line segment that passes through the midpoint of the circle and joins any point on the circumference is the diameter. Diameter is two times the size of the radius of a circle. A line segment with its endpoints on the circumference of the circle, not passing through the midpoint is called a chord. Ref fig.4.
It is important to remember that an infinite number of radii, diameters, and chords can be drawn in a circle. They are all congruent or equal, but not the same. All Radii and all diameters of a circle are congruent, but their position in the construction of a circle makes each one different. The circumference of a circle is the outer ring of a circle. It is the distance that goes around a circle i.e., its outer boundary.
(images will be uploaded soon)