Plane Figures Payalg Ldh

GOVT. GIRLS HIGH SCHOOL, PAYAL Project Name:- Area Of Plane Figures Student’s Name

Class

Manpreet Kaur Prabhdeep Kaur Parminder Kaur

7th A 7th B 7th B

Plane Figures 1) Quadrilateral 2) Circle 3) Triangle

(A) Quadrilateral Definition: The plane enclosed by four sides as line –segment is called quadrilateral. Types of Quadrilateral:-1. Trapezium 2. Parallelogram 3. Rhombus 4. Rectangle 5. Square 1) Trapezium:- A quadrilateral in which a pair of opposite sides are parallel. Trapezium ABCD in which AB||DC Area of Trapezium= 1/2(b1+b2)*h

E.g.:- Find the area of trapezium whose base are 6 cm & 8 cm and height of trapezium is 7 cm b1 = 6 cm, b2 = 8 cm, h = 7 cm Area of Trapezium = ½ (b1+b2)*h = ½ (6 + 8) * 7 = ½ (14) * 7 = 7 *7 = 49 cm2

2) Parallelogram:- If both the pairs of opposite sides of quadrilateral are parallel , then it is called a parallelogram. Parallelogram ABCD in which AD||BC and AB||DC. Area of parallelogram = b*h

E.g.:- Find the area of parallelogram whose length & breath are 7 cm & 8 cm. L = 7 cm, B = 8 cm Area of parallelogram = L * B =7*8 = 56 cm2 3) Rhombus:- A quadrilateral in which opposite sides are parallel as well as equal. Rhombus ABCD in which AD||BC and AB||DC and AB=BC=CD=DA Area of Rhombus=b*h

E.g.:- Find the area of Rhombus whose breath & height are 6 cm & 4 cm. L = 6 cm, B = 4 cm Area of Rhombus = L * B =6*4 = 24 cm2 4.) Rectangle:- If one angle of a parallelogram is 900, then it becomes a rectangle. Rectangle ABCD in which
E.g.:- Find the area of rectangle whose length & breath are 7 cm & 8 cm. L = 7 cm, B = 8 cm Area of rectangle = ½ * L * B =½ *7*8 = ½ * 56 = 28 cm2

5) Square:-If in a parallelogram, adjacent sides are equal and one angle is 900 then its a square. Square ABCD in which AB=BC=CD=DA and
E.g.:- Find the area of square whose side is 7 cm S = 7 cm Area of square = 2 * S =2*7 = 14 cm2

B) Circle Circle:-Circle is a closed figure consist all those points of a plane through a point which are at a constant distance from a point. . Point ‘O’ is the centre of circle.

‘OP’ is radius of circle.

Area of circle =∏r2 ∏ = 3.14 or 22/7 r is radius

E.g.:- Find the area of circle of radius is 10 CM. Area of circle A = IIr2 =3.14*10*10 =314 cm2

(C) Triangle Triangle:- The plane enclosed by 3 sides as line – segments is called triangle. It is denoted by ... Classification of triangle as its sides 1. Scalene triangle 2. Isosceles triangle 3. Equilateral triangle 1)Scalene triangle :- If all the 3 sides of a triangle are of different length , triangle is called a scalene triangle. Where a,b,c are three sides of triangle Area of

= where

E.g. find the area of

whose sides are 6cm, 8cm and 10cm.

a = 6cm, b = 8cm, c = 10cm S = (a+b+c)/2 = (6+8+10)/2 = 24/2 = 12 Area of

=

= = =

S = ( a+b+c)/2

= 24 cm2

2) Isosceles triangle:- If at least two sides of a triangle are of same length , triangle is called on isosceles. Where a=b Area of = where S = (a+b+c)/2

E.g:- The Hypotenuse of an isosceles triangle is 8 and are of its equal sides is 10cm. Find area of . a = b = 10cm c=8 S = (10 +10+8)/2 = 28/2 = 14 Area of

= = = = 36.66 cm2

3) Equilateral triangle :- If all the 3 sides of a triangle are equal length , triangle is called and equilateral triangle.

Area of

=

E.g:- one side of equilateral triangle is 10cm. Find the area Area of

= ¾(10)2 = ¾*100 = 75 cm2

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