Selina Concise Class 8 Math Chapter 20 Area of a Trapezium and a Polygon Exercise 20C Solution

Concise Mathematics – Class 8 Selina Exercise 20C Solution by experts | 20C Selina Concise Solution Class 8 | Class 8 Selina Concise Ex 20C Solution | RK Bansal Class 8 ICSE Book Solution Online.

Exercise 20C Solution

(1) The following figure shows the cross section ABCD of a swimming pool which is a trapezium in shape.

If the width DC, of the swimming pool is 6.4 m, depth (AD) at the shallow end is 80 cm and depth (BC) at the deepest end is 2.4 m, find its area of cross section.

(2) The parallel sides of a trapezium are in the ratio 3:4. If the distance between the parallal sides is 9 dm and its area is 126 dm square, find the lengths of its parallal sides.

Solution:

(3) The two parallel sides and the distance between them are in the ratio 3:4:2. If the area of the trapezium is 175 cm square, find its height.

(4) A parallelogram has sides of 15 cm and 12 cm. If the distance between the 15 cm sides is 6 cm, find the distance between 12 cm sides.

Solution:

(5) A parallelogram has sides of 20 cm and 30 cm. If the distance between its shorter sides is 15 cm, find the distance between the longer sides.

Solution:

(6) The adjacent sides of a parallelogram are 21 cm and 28 cm. If its one diagonal is 35 cm, find the area of the parallelogram.

Solution:

(7) The diagonals of a rhombus are 18 cm and 24 cm, find:

(i) Its area

(ii) Length of its sides

(iii) Its perimeter

Solution:

(8) The perimeter of a rhombus is 40 cm. If one diagonal is 16 cm, find:

(i) its other diagonal

(ii) area

(9) Each side of a rhombus is 18 cm. If the distance between two parallal sides is 12 cm, find its area.

Solution:

(10) The length of the diagonals of a rhombus is in the ratio 4:3. If its area is 384 cm square, find its side.

Solution:

(11) A thin metal iron-sheet is a rhombus in shape with each side 10m. If one of its diagonal is 16 m, find the cost of painting its both sides at the rate of Rs. 6 per meter square.

Also find the distance between the opposite sides of this rhombus.

(12) The area of a trapezium is 279 sq. cm and the distance between its two parallal sides is 18 cm. if one of its parallel sides is no longer than the other side by 5 cm,find the lengths of its parallal sides.

Solution:

(13) The area of a rhombus is equal to the area of a triangle. if base of triangle is 24 cm, its corresponding altitude is 16 cm and one of the diagonals of the rhombus is 19.2 cm, find its other diagonal.

Solution:

(14) Find the area of the trapezium ABCD in which AB//DC, AB = 18 cm, ∠B = ∠C = 90, CD = 12 cm and AD = 10 cm.

Solution:

3 Comments

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  1. Very helpful but in question number 9 height spelling is incorrect

    1. Ok we will correct it Rahul

  2. its very helpful for my exams thank you

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