Selina Concise Class 8 Math Chapter 22 Area Of A Trapezium And a Polygon Exercise 20A Solution
Concise Mathematics – Class 8 Selina Exercise 20A Solution by experts | 20A Selina Concise Solution Class 8 | Class 8 Selina Concise Ex 20A Page 223 to 224 Solution | RK Bansal Class 8 ICSE Book Solution Online.
(1) Find the area of a triangle; whose sides are:
(i) 10cm, 24cm and 26cm
(ii) 18 mm, 24 mm and 30 mm
(iii) 21 m , 28 m and 35 m
Solution:
(2) Two sides of a triangle are 6 cm and 8 cm. If height of the triangle corresponding to 6 cm side is 4 cm; find:
(i) area of the triangle
(ii) height of the triangle corresponding to 8 cm side.
Solution:
(3) The sides of a triangle are 16 cm, 12 cm and 20 cm. Find :
(i) area of the triangle
(ii) height of the triangle, corresponding to the largest side.
(iii) height of the triangle, corresponding to the smallest side.
Solution:
(4) Two sides of a triangle are 6.4 m and 4.8 m. If height of the triangle corresponding to 4.8 m side is 6 m; find:
(i) area of the triangle;
(ii) height of the triangle corresponding to 6.4 m side.
Solution:
(5) The base and the height of a triangle are in the ratio 4:5. If the area of the triangle is 40 m2; find its base and height.
Solution: Let the base be 4x m and height be 5x m.
(6) The base and the height of a triangle are in the ration 5:3. If the area of the triangle is 67.5 meter square, find its base and height.
Solution:
(7) The area of an equilateral triangle is 144√3 cm square, find its perimeter.
(8) The area of an equilateral triangle is numerically equal to its perimeter. Find its perimeter correct to 2 decimal places.
Solution:
(9) A field is in the shape of a quadrilateral ABCD in which AB = 18 m, side aD = 24 m, side BC = 40 m, DC = 50 m and angle A = 90 degree. Find the area of the field.
Solution:
(10) The lengths of the sides of a triangle are in the ratio 4:5:3 and its perimeter is 96 cm. Find its area.
(11) One of the equal sides of an isosceles triangle is 13 cm and its perimeter is 50 cm. Find the area of the triangle.
Solution:
(12) The altitude and the base of a triangle field are in the ratio 6:5. If the cost is Rs. 49,57,200 at the rate of Rs. 36,720 per hectare and 1 hectare = 10,000 sq.m, find (in metre dimensions of the field.
Solution:
Or x2 = 90000
∴ x = 300
∴ Base = (5 x 300) m
= 1500 m
Altitude = (6 x 300) m
= 1800 m.
(13) Find the area of the right angled triangle with hypotenuse 40 cm and one of the other two sides 24 cm.
Solution:
(14) Use the information given in the adjoining figure to find:
(i) the length of AC
(ii) the area of triangle ABC
(iii) the length of BD, correct to one decimal place.
Solution:
___ x ___
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