Geometric Constructions

In Geometric Constructions, we will discuss different types of constructions, such as copy of line segment, bisect the line segment,copy of an angle or bisect the given angle etc.

Constructions in Geometry means to draw shapes, angles or lines accurately.

These constructions use only compass, straightedge (i.e. ruler) and a pencil.

This is the "pure" form of geometric construction - no numbers involved!

In drawing the geometric shapes, we need to use some geometrical tools.


Some Geometrical tools :

1) Ruler : It is smaller than a meter scale. Generally it is 6 inches or (approximately 15cm). It has centimeter and millimeter marks on one edge. The opposite edge has inch marks. The marks on the ruler are called graduations and the ruler is called a graduated scale.




2) Divider : Geometry dividers are used for transferring measurements from one part of the drawing to another.




3) Compass : It is an instrument with two metal arms. One of the arm has metal end point and the other arm has a screw arrangement which can hold a pencil tightly. The distance between the two arms can be adjusted. It is used to draw an angle, circle, arc etc.




4) Protractor : It is used to measure angle. It has a degree marks on the semicircular arc which ranges from 0 -180. The mid point is at 90. The angle between two consecutive marks is 1⁰. The marks written on curved edge at an interval of 10⁰




5)Set-squares : There are two types of set squares 1) 60-30 set squares 2) 45 set squares. They are used to construct 30,45,60 and 90 degree angles. Also they are used to draw parallel and perpendicular lines.

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Geometrical Constructions

• Basic Geometric Constructions
• Construction of Line Segment
• Bisecting a Line Segment
• Constructing Angles
• Bisecting Angles
• Constructing Parallel Lines
• Construction of Triangle (SSS)
• SAS Triangle Construction
• ASA Triangle Construction
• HL Triangle Construction (Rhs -construction)
• Constructing Quadrilaterals
• Constructing Triangles(when sum of sides or perimeter is given)

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