CBSE | NCERT CLASS

What is Polygon? a plane figure with at least three straight sides and angles, and typically five or more . Example of Polygons: Triangle, quadrilateral, pentagon, hexagon, heptagon, octagon, nonagon, decagon according as it contains 3,4,5,6,7,8,9,10 sides respectively.

Area of Polygon CBSE Class VIII Maths The plots and fields are in the form of regular or irregular polygons. We find their areas by dividing them into triangles, rectangles, parallelograms and trapeziums. 1. In the give figure, PQRS is a quadrilateral in which PR=32m, QX perpendicular PR,   SY perpendicular PR such that QX=10m and SY=8m. Find the area of the quad PQRS. Answer:

Area of a Trapezium, CBSE NCERT (Class 8, 9,10) Trapezium : A trapezium is a quadrilateral having one pair of parallel opposite sides.

Probability In our day-to-day life we here statements like: most probably it will rain today, chances are high that the prices of petrol will go up, I doubt that he will win the race. The words ‘most probably’, ‘chances’, ‘doubt’ show the probability of occurrence of an event. Experiment : An operation which can produce some well defined outcomes is called an experiment. Each outcome is called an event.

Friction: The force which resists the motion of a body while moving on a surface is called friction. Some properties of friction: (i) Friction depends on the nature of surfaces in contact. (ii) Frictional force does not depends on the surface area. (iii) It is acts in a direction opposite to the direction of motion.

Cell: Structure and Function Brief History of Cell Discovery An English scientist, Robert Hooke, discover cell in 1665 . When he was examining a dried section of cork tree with his own made light microscope, he saw many honeycomb like empty chambers in it. He named each hollow space as cell. After his discovery of cell, considerable progress has been made in the development of powerful and more sophisticated microscopes. In 1831, Scottish scientist Robert Brown named nucleus of a cell. In 1839, Parkenje named Protoplasm . In 1839, Schleidon and Schwamm together announced cell theory -

Factorisation Factors: When an algebraic equation can be written as the product of two or more expressions then each of these is called a factor of the give equation. Factorisation: The process of finding two or more expressions whose product is the given expression is called factorisation.