The document provides formulas and concepts for calculating area, perimeter, volume, and surface area in geometry. Key formulas include the area of a triangle (0.5 x base x height), parallelogram (base x height), trapezium, circle (circumference and area), and volumes of cuboids and cubes. Additionally, it explains how surface area can be calculated using nets, which are 2-dimensional shapes that can form 3-dimensional solids.

1. MATHEMATICS
Student Led Conference

2. AREA, PERIMETER AND
VOLUME
Understanding the concepts

3.  The formula for the area of a triangle
is [0.5 X b X h]
 There is a reason for this formula.
AREA OF A TRIANGLE
base
height
b X h
2
Formula: 0.5 X b X h
= 0.5 X 12 x 11.5 cm
= 6 X 11.5 cm
=69 cm

4. AREA OF A PARALELLOGRAM
 The area of a parallelogram is [b X h]
 Remember: Always use the perpendicular height.
 There is reason behind this formula as well.
h
b
Question:
Formula = b*h
=3 X 9
=27 cm2

5. AREA OF TRAPEZIUM
 The area of a trapezium is a+b X h
 Concept of this formula:
2
a
b
h
h
a b
Question:
Formula: a+b X h
2

6. CIRCUMFERENCE AND AREA OF A CIRCLE
 Circumference: 2πr
 π=22/7 or 3.14
 Area: πr2
 π=22/7 or 3.14
Formula= 2πr
=2 X 3.14 X 5
=62.8 m
Formula= πr2
=3.14 X 52
=78.5 m2

7. VOLUME
 It is the amount of space that a substance or object occupies.
 Formula of volume of a cuboid = lwh
 Formula of Volume of a cube: s3
 Question-
Find the volume of a cuboid:
4 X 2 X 10
= 80 cm3

8. SURFACE AREA
 The total area of the surface of a three-dimensional object.
 Surface area of cuboid = 2lw + 2lh + 2wh = 2(lw +lh + wh)
 Question:
2 (4*2 + 6*2.5 + 6*4)
=94mm2

9. SURFACE AREA USING NETS
 We can also calculate surface area using nets.
 A net is a 2-dimensional shape that can be folded to form a 3-dimensional
shape or a solid.
 Question ->>