Topics
Number Systems
Number Systems
Algebra
Polynomials
Linear Equations in Two Variables
Algebraic Expressions
Algebraic Identities
Coordinate Geometry
Geometry
Introduction to Euclid’S Geometry
Lines and Angles
Triangles
Quadrilaterals
 Concept of Quadrilaterals  Sides, Adjacent Sides, Opposite Sides, Angle, Adjacent Angles and Opposite Angles
 Angle Sum Property of a Quadrilateral
 Types of Quadrilaterals
 Theorem: A Diagonal of a Parallelogram Divides It into Two Congruent Triangles.
 Another Condition for a Quadrilateral to Be a Parallelogram
 The Midpoint Theorem
 Theorem: A Diagonal of a Parallelogram Divides It into Two Congruent Triangles.
 Property: The Opposite Sides of a Parallelogram Are of Equal Length.
 Theorem : If Each Pair of Opposite Sides of a Quadrilateral is Equal, Then It is a Parallelogram.
 Property: The Opposite Angles of a Parallelogram Are of Equal Measure.
 Theorem: If in a Quadrilateral, Each Pair of Opposite Angles is Equal, Then It is a Parallelogram.
 Property: The diagonals of a parallelogram bisect each other. (at the point of their intersection)
 Theorem : If the Diagonals of a Quadrilateral Bisect Each Other, Then It is a Parallelogram
Area
Circles
 Concept of Circle  Centre, Radius, Diameter, Arc, Sector, Chord, Segment, Semicircle, Circumference, Interior and Exterior, Concentric Circles
 Angle Subtended by a Chord at a Point
 Perpendicular from the Centre to a Chord
 Circles Passing Through One, Two, Three Points
 Equal Chords and Their Distances from the Centre
 Angle Subtended by an Arc of a Circle
 Cyclic Quadrilateral
Constructions
Mensuration
Areas  Heron’S Formula
Surface Areas and Volumes
Statistics and Probability
Statistics
Probability
notes
Collecting Data:
Temperatures of cities as on 20.6.2006 

City 
Max. 
Min. 
Ahmedabad  38°C  29°C 
Amritsar  37°C  26°C 
Bangalore  28°C  21°C 
Chennai  36°C  27°C 
Delhi  38°C  28°C 
Jaipur  39°C  29°C 
Jammu  41°C  26°C 
Mumbai  32°C 
27°C 
What do these collections of data tell you?
The data about the temperatures of cities can tell us many things, For example, you can say that the highest maximum temperature was in Jammu on 20.06.2006 but it cannot tell us the city which had the highest maximum temperature during the year. To find that, we need to collect data regarding the highest maximum temperature reached in each of these cities during the year. In that case, the temperature chart of one particular date of the year, as given in the table will not be sufficient. This shows that a given collection of data may not give us specific information related to that data.
For this, we need to collect data keeping in mind that specific information. In the above case, the specific information needed by us was about the highest maximum temperature of the cities during the year, which we could not get from the Table. Thus, before collecting data, we need to know what we would use it for.

When the information was collected by the investigator herself or himself with a definite objective in her or his mind, the data obtained is called primary data.

When the information was gathered from a source which already had the information stored, the data obtained is called secondary data.
Such data, which has been collected by someone else in another context, needs to be used with great care ensuring that the source is reliable.