STD VIII – GEOMETRY (Online)

GEOMETRY

Understanding Shapes

The word ‘quad’ means four and the word lateral means sides. Thus, a plane figure bounded by four-line segments AB, BC, CD and DA is called a quadrilateral and is written as quad ABCD.

A quadrilateral has four sides, four angles, four vertices and two diagonals. Quadrilaterals can be classified into different types based on their sides and angles. In this topic, we shall learn the different types of quadrilaterals and their properties.

Special Types of Quadrilaterals

In Euclidean plane geometry, a quadrilateral is a polygon with four edges (or sides) and four vertices or corners. Sometimes, the term quadrangle is used, by analogy with triangle, and sometimes tetragon for consistency with pentagon (5-sided), hexagon (6-sided) and so on.

Quadrilaterals

Trapezium | Kite | Parallelogram | Rhombus | Rectangle | Square

Constructions

Geometrical construction means to draw shapes, angles or lines accurately. These constructions use only compass, ruler and a pencil. In this topic, we shall learn some basic constructions used in Geometry.

Represent 3 – D in 2 – D

A geometric shape is a geometric information which remains when location, scale, orientation and reflection are removed from the description of a geometric object.

That is, the result of moving a shape around, enlarging it, rotating it, or reflecting it in a mirror is the same shape as the original, and not a distinct shape. When architects design buildings they often sketch 2D drawings to show what the building will look like from each side. These drawings are called plans and elevations.

In this topic, you would be able to visualize 2D cross sections of representations of 3D objects.