1a. 98 cm ^2
1b. 76. 98 cm^2
2a. 42cm
2b. 7. 19 cm
3. a + b/2 (h)
4. 24 cm ^2
5. πr + 2r
6. 13. 2m
7. 45cm^2
8. 252 cm ^ 2
9. 450 cm^ 2
1a. The shape given is a rectangle
The formula for area of a rectangle is given as;
Area = length × width
Area = 7 × 14
Area = 98 cm ^2
1b The shape given is a semi circle
The formula for area of a semicircle is given as;
Area = 1/2 π r^2
radius = diameter/2 = 14/2 = 7cm
Area = 1/2 × 3.142 × 7 × 7
Area = 76. 98 cm^2
2a. The shape given is a rectangle
The formula for perimeter of a rectangle is given as;
Perimeter = 2 ( length + width)
Perimeter = 2 ( 14 + 7) = 2( 21)
Perimeter = 42cm
2b. The shape is a semicircle
Perimeter = π r + 2r
r= 1.4cm; diameter divided by 2
Perimeter = 3. 142(1.4) + 2(1.4)
Perimeter = 7. 19 cm
3. The formula for area of a trapezium is given as
Area = a + b/2 (h)
4. The area of the trapezium is given as;
Area = 9 + 7/2 (3)
Area = 16/2 (3)
Area = 8 × 3
Area = 24 cm ^2
5. Area of semicircle = 1/2 πr^2
Perimeter of a semicircle = πr + 2r
6. From the information given, we have the following
Area = 480 m^2
a = 20m
b = unknown
h = 13. 2m
Area = a+b/2 (h)
Substitute the values
480 = 20+b/2 (13. 2)
480 = 10+ b (13. 2)
480/13. 2 = 10 + b
10+ b = 480/ 13. 2
10 + b = 36. 36
b = 36.36 - 10
b = 26. 36m
7. The formula for area of a rhombus is given as
Area = p × q/2
Where p and q are the diagonals
Area = 7. 5 × 12/2
Area = 90/2
Area = 45cm^2
8. The formula for area for a quadrilateral is given as;
Area of quadrilateral = (½) × diagonal length × sum of the length of the perpendiculars
sum of the length = 13 + 8 = 21cm
Diagonal A= 24cm
Area = 1/2 × 24 × 21
Area = 252 cm ^ 2
9. Area of a pentagonal park = 1/2 × sum of parallel sides × height
Sum of parallel sides = 15 + 15 = 30 cm
height = 30cm
Area = 1/2 × 30 × 30
Area = 450 cm^ 2
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