Page 70 - WCS - Electrical

5 What is the side of the largest square cut out from a
1
5 What is the side of the largest square cut out from a
1
= x 50 x 16 cm
circle of 50 cm dia.?
= x 50 x 16 cm
circle of 50 cm dia.?
5 What is the side of the largest square cut out from a
2
1
Diagonal of a square = Diameter of the circle
= 400 cm
2
circle of 50 cm dia.?
2
Diagonal of a square = Diameter of the circle
= 400 cm
2
2a
= 50
2
r π
Diagonal of a square = Diameter of the circle
= 400 cm
2
unit
Area of Semi circle
= 2a
2
r π
2
unit
=
Area of Semi circle
2
2
50
2
r π
=
unit
a
=
50
2
1
a
2 =
2
2
π
x cm
=
50
2
15
π
x
=
x cm
=
a 2a = 50 2 x 15 = 50 2 2 2 2 Area of Semi circle = x 50 x 16 cm 2 2 1 2 2
50 2 1 2
2

= = 353.57 cm 50 = π x 15 x cm 2
2
2
=
1.414 WORKSHOP CALCULATION & SCIENCE - CITS = 353.57 cm 2
1.414
50
Total area of the figure= 500 + 400 + 353.57
= 353.57 cm
2
= 35.36 cm = Total area of the figure= 500 + 400 + 353.57
1.414 = 35.36 cm
= 1253.57 cm 2 2
= 1253.57 cm

6 Calculate the area of the figure given below. = 35.36 cm Total area of the figure= 500 + 400 + 353.57
6 Calculate the area of the figure given below.
7 Find the area of remaining steel plate if in a rectangular
7 Find the area of remaining steel plate if in a rectangular steel plate 16 cm x 12 cm, there are 6 holes each 4 = 1253.57 cm 2
7 Find the area of remaining steel plate if in a rectangular
steel plate 16 cm x 12 cm, there are 6 holes each 4
cm in diameter. 6 Calculate the area of the figure given below. steel plate 16 cm x 12 cm, there are 6 holes each 4
cm in diameter. 7 Find the area of remaining steel plate if in a rectangular
cm in diameter.
Area of a rectangular plate = length x breadth unit 2 steel plate 16 cm x 12 cm, there are 6 holes each 4
Area of a rectangular plate = length x breadth unit
cm in diameter. 2
= 16 x 12
Area of a rectangular plate = length x breadth unit 2
= 16 x 12
= 192 cm 2
= 16 x 12= 192 cm 2
No. of holes = 6
No. of holes 2
= 192 cm= 6
Radius of hole = 2 cm No. of holes = 6le = 2 cm
Radius of ho
Area of rectangle
= lb unit
5 What is the side of the largest square cut out from a Area of 6 holes = 6 x πr unit 2 2
2
1
2
= x 50 x 16 cm
Area of 6 holes
circle of 50 cm dia.? = 25 x 20 cm 2 Area of rectangle = lb unit 2 Radius of hole = 2 cm = 6 x πr unit 2
2
2
= 25 x 20 cm
2
2
Diagonal of a square = Diameter of the circle Area of rectangle = lb unit 22 2 2 Area of 6 holes = 6 x πr unit 2
= 400 cm
= 500 cm 2 = 6 x x 2 x 2 unit 2 22
= 25 x 20 cm 2 2 = 6 x x 2 x 2 unit 2
7 = 500 cm
2a = 50 r π 2 22 7
1
=
2
Area of Trapezium = x (a + b) h Area of Semi circle = 500 cm unit 2 2 = 6 x x 2 x 2 unit 2
1
= 75.43 cm
2
2 50 Area of Trapezium = x (a + b) h 7 = 75.43 cm 2
2
1
Area of remaining plate = 192 - 75.43
a = 1 Area of Trapezium = x (a + b) h Area of remaining plate = 192 - 75.43
= 75.43 cm
2
= x (30 + 20) 16 cm 2 2 π x 15 2 x 1 2 2
2
1
= 116.57 cm cm
2 = = x (30 + 20) 16 cm 2 Area of remaining plate = 192 - 75.43 2
2
= 116.57 cm
50 1 2 2
= = x (30 + 20) 16 cm = 116.57 cm 2
= 353.57 cm
2
2
Semi circle 1.414 Examples Semi circle
Total area of the figure= 500 + 400 + 353.57
= 35.36 cm Examples
A semi circle is a sector whose central angle is 180º. Semi circle = 1253.57 cm 2
Semi circle
1 Calculate the circumference and area of a semi circle
A semi circle is a sector whose central angle is 180º.
Length of arc of semi circle.
6 Calculate the area of the figure given below. whose radius is 6 cm. Examples 1 Calculate the circumference and area of a semi circle
A semi circle is a sector whose central angle is 180º.
Length of arc of semi circle.
whose radius is 6 cm.
7 Find the area of remaining steel plate if in a rectangular
180 A semi circle is a sector whose central angle is 180º. 1 Calculate the circumference and area of a semi circle
radius r
Length of arc  = 2πr x Length of arc of semi circle. = 6 cm 180 whose radius is 6 cm. = 6 cm
steel plate 16 cm x 12 cm, there are 6 holes each 4
radius r
Length of arc  = 2πr x
Length of arc
360 cm in diameter. l l 180 360
= ?
Area A
1 Length of arc  = 2πr x 2 radius r Area A = 6 cm = ?
Area of a rectangular plate = length x breadth unit
360
= 2πr x = πr unit Circumference c = ? 1
= ?
2 = 2πr x = πr unit Area A Circumference c = ?
2
r π
1 = 16 x 12 2
=
unit
A
r π 2 = 2πr x = πr unit 2 2 Circumference c = ? r π 2
2
2
Area of semi circle = Sq. units 2= 192 cm A = 2 unit 2
r π
2 Area of semi circle = Sq. units r π 2
No. of holes r π 2 = 6 22 2 A = unit 2
Area of semi circle = Sq. units 1 2 2 22 1
=
x x 6
Radius of hole 2 = 2 cm 2 = x x 6 2
7
7
1
Area of rectangle = lb unit 2 Area of 6 holes = 6 x πr unit 2 = 22 x x 6 2 2
2
22
1
= 25 x 20 cm 2 Area (A) = x x 36 7 2 22 1
7 22 2 Area (A) = x x 36
= 500 cm 2 = 6 x x 2 x 2 unit 2 22 1 7 2
2πr 396 7 Area (A) = 7 x x 36
2
= 56.57 cm
1
=
Perimeter of a semi circle = + 2r = 75.43 cm 2 2πr 2 = 396 = 56.57 cm 2
7
Area of Trapezium = x (a + b) h
2 2 Perimeter of a semi circle = 2 + 2r 396 7
2πr
= πr + 2r Perimeter of a semi circle = + 2r = = 56.57 cm 2
22
Area of remaining plate = 192 - 75.43
1
7
2
x 2)

= x (30 + 20) 16 cm 2 Perimeter of a semicircle = 6( = πr + 2r Perimeter of a semicircle = 6( 22 x 2)
7
= r (π + 2) unit
= 116.57 cm
2
2
7
= πr + 2r = r (π + 2) unit
22
WCS - Electrician & Wireman : (NSQF - Revised 2022) - 1 Year : Exercise 1.7.26 65 Perimeter of a semicircle = 6( 7 x 2)
st
= r (π + 2) unit
WCS - Electrician & Wireman : (NSQF - Revised 2022) - 1 Year : Exercise 1.7.26
st
Semi circle WCS - Electrician & Wireman : (NSQF - Revised 2022) - 1 Year : Exercise 1.7.26 65
st
Examples Examples 65
A semi circle is a sector whose central angle is 180º.
1 Calculate the circumference and area of a semi circle
Length of arc of semi circle. 1 Calculate the circumference and area of a semi circle whose radius is 6 cm.
whose radius is 6 cm.
180
Length of arc  = 2πr x radius r = 6 cm
360
Area A = ?
1
= 2πr x = πr unit Circumference c = ?
2
r π 2
r π 2 A = unit 2
Area of semi circle = Sq. units 2
2
57 22 1
=
x x 6
2
CITS : WCS - Electrical - Exercise 5
2
7
22 1
Area (A) = x x 36
7 2
2πr 396
Perimeter of a semi circle = + 2r = = 56.57 cm 2
2 7
= πr + 2r 22
= r (π + 2) unit Perimeter of a semicircle = 6( 7 x 2)
WCS - Electrician & Wireman : (NSQF - Revised 2022) - 1 Year : Exercise 1.7.26 65
st