You have studied about triangles and their various properties in your earlier classes.
You know that a closed figure formed by three intersecting lines is called a triangle.
(Tri means three). A triangle has three side
AREAS OF PARALLELOGRAMS AND TRIANGLES
In Chapter 5, you have seen that the study of Geometry, originated with the
measurement of earth (lands) in the process of recasting boundaries of the fields and
You have studied many properties of a triangle in Chapters 6 and 7 and you know that
on joining three non-collinear points in pairs, the figure so obtained is a triangle. Now,
let us mark four points and see what
Whats the good of Mercators North Poles and Equators, Tropics, Zones and
Meridian Lines? So the Bellman would cry; and crew would reply They are
merely conventional signs!
LEWIS CARROLL, The Hunting of the Snark
You may have come across many objects in daily life, which are round in shape, such
as wheels of a vehicle, bangles, dials of many clocks, coins of denominations 50 p,
Re 1 and Rs 5, key rings, buttons
LINES AND ANGLES
In Chapter 5, you have studied that a minimum of two points are required to draw a
line. You have also studied some axioms and, with the help of these axioms, you
proved some other statements. In this chapter, y
In your earlier classes, you have learnt about the number line and how to represent
various types of numbers on it (see Fig. 1.1).
Fig. 1.1 : The number line
Just imagine you start from zero and g
You have studied algebraic expressions, their addition, subtraction, multiplication and
division in earlier classes. You also have studied how to factorise some algebraic
expressions. You may recall th
SURFACE AREAS AND VOLUMES
Wherever we look, usually we see solids. So far, in all our study, we have been dealing
with figures that can be easily drawn on our notebooks or blackboards. These are
called plane fi