# Selina Solutions Concise Maths Class 8 Chapter 20: Area of Trapezium and Polygon

Selina Solutions Concise Maths Class 8 Chapter 20 Area of Trapezium and Polygon provides students with accurate answers to the textbook problems in a systematic manner. A set of highly experienced faculty at BYJUâ€™S curate these solutions with the aim of improving the knowledge about the basic concepts among students. In order to obtain a clear view about the concepts explained here, students can download the ICSE Selina Solutions Class 8 Maths Chapter 20 Area of Trapezium and Polygon PDF, from the link provided below.

From this chapter, it will be easy for the students to understand the method of determining the area, height, perimeter and length of the given figures. Regularly solving the textbook questions using these solutions will enhance the problem solving skills among the students, which is important from the exam perspective.

## Access Selina Solutions Concise Maths Class 8 Chapter 20: Area of Trapezium and Polygon

Exercise

QuestionÂ 1.Â

Find the area of a triangle, whose sides are:

(i)Â 10cm, 24cmÂ andÂ 26cm

Solution:-

Sides ofÂ Î”Â are

a=10cm

b=24cm

c=26cm

(ii)Â 18mm, 24 mmÂ andÂ 30mm

Solution:-

Sides ofÂ Î”Â are

a=18mm

b=24mm

C=30mm

(iii)Â 21 m, 28 mÂ andÂ 35 m

Solution:-

Sides ofÂ Î”Â are

a=21m

b=28m

c=35m

QuestionÂ 2.Â

Two sides of a triangle areÂ 6 cmÂ andÂ 8 cm. If height of the triangle corresponding toÂ 6 cmÂ side isÂ 4 cm;Â find.

(i) Area of the triangle

(ii) Height of the triangle corresponding to 8 cm side.

Solution:-

BC=6cm

Height AD=4cm

(i)Â 12cm2Â (ii)3cm

Question 3.Â

The sides of a triangle areÂ 16cm, 12cmÂ andÂ 20cm. 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:-

Sides ofÂ Î”Â are

a=20cm

b=12cm

c=16cm

Question 4.Â

Two sides of a triangle areÂ 6.4 mÂ andÂ 4.8 m. If height of the triangle corresponding toÂ 4.8mÂ side isÂ 6m; find:

(i) Area of the triangle;

(ii) height of the triangle corresponding to 6.4 m side.

Solution:-

ABCÂ is theÂ Î”Â in which BC=4.8m

AC=6.4mÂ andÂ AD=6m

QuestionÂ 5.

The base and the height of a triangle are in the ratioÂ 4:5.Â If the area of the triangle is 40Â m2;Â find its baseÂ Â and height.

Solution:-

Question 6.Â

The base and the height of a triangle are in the ratioÂ 5:3.Â If the area of the triangle isÂ 67m2.find its baseÂ and height.

Solution:-

Consider baseÂ =5Ã—m

HeightÂ =3Ã—m

QuestionÂ 7.

Question 8.Â

The area of an equilateral triangle is numerically equal to its perimeter. Find its perimeter correct toÂ 2Â decimal places.

Solution:-

Â Consider each side of the equilateral triangleÂ = x

Question 9.Â Â

A field is in the shape of a quadrilateralÂ ABCDÂ in which sideÂ AB = 18m,Â sideÂ AD = 24m,Â sideÂ BC = 40m, DC = 50mÂ and angleÂ A = 90Â°.Â Find the area of the field.

Solution:-

âˆ A=90Â°

By Pythagoras Theorem,

InÂ âˆ†ABD,

QuestionÂ 10.Â

TheÂ lengthsÂ ofÂ theÂ sidesÂ ofÂ aÂ triangleÂ areÂ inÂ theÂ ratioÂ 4Â :Â 5Â :Â 3Â andÂ itsÂ perimeterÂ isÂ 96Â  cmÂ .Â FindÂ itsÂ area.

Solution:-

Consider theÂ sidesÂ ofÂ theÂ triangleÂ ABCÂ beÂ 4Â x,Â 5 xÂ andÂ 3x

AB=4Â x,Â AC=5Â xÂ andÂ BC=3Â x

PerimeterÂ = 4Â x+5x+3x=96

12Â x=96

Â QuestionÂ 11.Â

One of the equal sides of an isosceles triangle isÂ 13cmÂ and its perimeter isÂ 50cm. Find the area of theÂ triangle.

Solution:-

Â In IsoscelesÂ Î”ABC

AB=AC=13cmÂ But perimeterÂ =50cm

BC=50-(13+13)cm

=50-26=24cm

ADâŠ¥BC

QuestionÂ 12.Â

The altitude and the base of a triangular field are in the ratioÂ 6:5.Â If its cost isÂ Rs.49, 57,200Â at the rate ofÂ Rs.36, 720Â per hectare andÂ 1Â hectareÂ =10,000Â sq.Â m,Â find (in meter) dimensions of the field,

Solution:-

Â Total costÂ =349,57,200

Rate = 736,720 per hectare

Total area of the triangular field

Â QuestionÂ 13.

Find the area of the right-angled triangle with hypotenuseÂ 40cmÂ and one of the other two sidesÂ 24cm.

Solution:-

Â In right angled triangle ABC Hypotenuse ACÂ =40cm

One sideÂ AB=24cm

QuestionÂ 14.

Use the information given in the adjoining figure to find:

(i) The length of AC.

(ii) The area of aÂ Î”ABC

(iii) The length of BD, correct to one decimal place.

Solution:-

Sol.Â AB=24cm, BC=7cm

Question 15.Â

Find the length and perimeter of a rectangle, whose areaÂ =120cm2Â and breadthÂ =8cm

Solution:-

Area of rectangleÂ =120cm2

Breadth,Â b=8cm