Articles

Triangles
Triangle is the simplest polygon of all the closed figures formed in a plane by three line segments. It is a closed figure formed by three line segments having six elements - three angles (i) ∠ABC or ∠B (ii) ∠ACB or ∠C (iii) ∠CAB or ∠A and three sides - (iv) AB (v) BC (vi) CA.

Concurrent Lines in Triangle
Two lines in a plane can either be parallel or intersecting. Three lines in a plane may (i) be parallel to each other (ii) intersect each other in exactly one point (iii) intersect each other in two points (iv) intersect each other at most in three points.

Quadrilaterals
If A, B, C and D are four points in a plane such that no three of them are collinear and the line segments AB, BC, CD and DA do not intersect except at their end points, then the closed figure made up of four line segments is called a quadrilateral with vertices A, B, C and D.

Introduction to Probability
In day to day life, we sometimes make the statements like "It may rain today" or "Train is likely to be late". The words (may, likely, unlikely, chances, doubt) show that the event, we are talking about, is not certain to occur. It may or may not occur.

Pressure and Winds
Air has weights and it exerts pressure which varies from place to place. These variations are specified ion pressure belts. The pressure at different location of the world also varies in different seasons. This variation causes the movement of air called winds.

Weather and Climate
The temperature, atmospheric pressure, winds and precipitation are main elements of weather have an important effect on our lives. For example the houses we construct, the clothes we wear and the food we prefer mainly depend on weather and climatic conditions.

Demand, Supply, Price and Market
Demand for a commodity refers to the quantity of the commodity that a buyer is willing to buy at given price at given time. Individual demand is the quantity of a commodity that an individual buyer is willing to buy at the given price at given time.

Money, Banking and Insurance
Before money was invented people used to exchange goods for goods which was called barter system. There were many problems of barter system such as absence of a common measure of value, lack of double coincidence of wants, lack of space to store goods to exchange them for other goods etc. This prompted human society to discover money.

NCERT Chapter Summary: The Fun They Had
This story is set in the future when children don’t have traditional books and schools. It is set about 150 years ahead. One day, Margie, a little girl in the story, makes a diary entry - ‘Today Tommy found a real book’.

NCERT Chapter Summary: The Midnight Visitor
1. Who was Ausable?
Ausable was a secret agent. A very important document concerning some new missiles was under his safe custody. He didn’t look like a secret agent as we read in books or see in films. He was fat and sloppy. His office was in a small room on the sixth and top floor. Fowler was very disappointed to meet him.

NCERT Chapter Summary: A Triumph of Surgery
1. Why was Dr. Herriot really worried about Tricki?
When Dr. Herriot saw Tricki with his mistress, he was really worried. He was shocked at his appearance. The dog had become hugely fat. His eyes were bloodshot and rheumy. His tongue lolled from his jaws. Naturally, the miserable condition of the dog made him really worried.

NCERT Chapter Summary: What, Where, How and When
1. Why do you think ordinary men and woman did not generally keep records of the what they did?
The ordinary men and woman generally did not keep records of what they did as they regarded it as a part of their daily routine and not anything important.

NCERT Chapter Summary: What Books and Burials Tell Us
1. What kind of evidence from burials do archaeologists use to find out whether there were social difference amongst those who were buried?
In Brahmagiri, archaeologists located a skeleton buried with 33 gold beads, 2 stone beads, 4 copper bangles and 1 conch shell. Some other skeletons were found but with only a few pots. This helped archaeologists to find out social differences of those who were buried.


NCERT Chapter Summary: The Making of Regional Cultures
India is a diverse country with a rich cultural heritage and a multitude of regional cultures. Each region in India has its own distinct language, customs, traditions, art forms, music, dance, and cuisine.