Friday 13 January 2012

Basic Constructions in Grade XI

Hello friends, today I am going to discuss the important article which is Basic Constructions. This article is important for all Grade XI students.
So friends let’s start with Basic Constructions
In geometry construction means to draw shape, angle, line triangle, square, rectangle (try Formula for Area of a Rectangle here), rhombus, parallelogram, etc. These construction use only straight edge compass and pencil. In this way we can say this is the pure form of geometric construction. The basic construction of the geometric shapes have  some own steps and some own rule  that are to be followed. In this article we would  learn how to construct a line, circle, and triangle.
Let’s start with how to construct a line
Line is easiest basic construction of geometry. These have some steps that is given below
In the first step you have to place the compass at one end of line.
In the second step you have to adjust the compass to slightly longer than the line length
In third step we have draw arc above and below the line.
In fourth step keeping the same compass width, draw arc form the other end of the line.
In fifth step we have to place ruler where the arcs cross, and end of the line.

Let’s know how to construct a circle:
For constructing circle we require either diameter or radius if we know either on of the things we can easily make the circle.
We just need to have a compass and a scale which can measure radius or diameter
Radius is always half of the diameter so when we need to draw the circle we measure the radius by scale and then put that distance into our compass.
We can take any point and draw circle.


Let’s know how to construct a triangle:
You know friends for triangle we need three lines. So first we draw a line with the help of compass and scale.
In second step we make an arc on first point, then make other arc at last point.
In third step where these points are intersecting each other we make point on that then we join both the ends of the line to that intersecting point.
As the name suggest it contains three angles who’s sum is equal to 1800 degree. If all the angles are equal then every angle has the value of 600 each as 180/3= 60
If one of the three angles is of 900 then the triangle is called right angle triangle
If two of the side of a triangle is equal then the triangle is called isosceles triangle
If one of the angles is greater than 900 degree then the triangle is called obtuse angle triangle.
In every triangle the sum of any two sides will always be greater than third side.
Note: the distance in which we are making arc should be equal distance from the point.


In the above article we have seen about lines circle and triangle. Hope you have understood all the things that I told to you.

In upcoming posts we will discuss about Conditional Statements and trigonometric ratios. Visit our website for information on CBSE 12th syllabus

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