S.chand books class 8 maths solution chapter 25 Areas of Rectilinear Figures exercise 25 E

 EXERCISE 25 E

---

Q1 | Ex-25E | Class 8 | S.Chand | Composite maths| Areas of Rectilinear Figures | Ch-25 |myhelper

OPEN IN YOUTUBE

Find the areas of the following polygons

Question 1

Sol :

Area of ΔAED$=\frac{1}{2}\times \text{base}\times \text{height}$

$=\frac{1}{2}\times 6 \times 8$

=24 cm²

Area of trapezium$=\frac{1}{2}\times \text{(sum of parallel)} \times \text{height}$

$=\frac{1}{2}\times (6+12) \times (13-8)$

$=\frac{1}{2} \times 18 \times 5$

=9×5=45 cm²

Total Area=Area of triangle+Area of trapezium

=24+45=69 cm²

---

Q2 | Ex-25E | Class 8 | S.Chand | Composite maths| Areas of Rectilinear Figures | Ch-25 |myhelper

OPEN IN YOUTUBE

Question 2

Sol :

Area of Hexagon$=\frac{3 \sqrt{3}}{2} a^{2}$

$=\frac{3 \sqrt{3}}{2} \times 8^{2}$

$=\frac{3 \sqrt{3} }{2}\times 8 \times 8$

$=96 \sqrt{3} \mathrm{~cm}^{2}$

$=96 \times 1.73=214.08 \mathrm{~cm}^2$

Area of rectangle=4×12=$48 \mathrm{~cm}^{2}$

Total Area =Area of rectangle + Area of hexagon

$=214.08+48 \mathrm{~cm}^2$

$=166.08 \mathrm{~cm}^2$

---

Q3 | Ex-25E | Class 8 | S.Chand | Composite maths| Areas of Rectilinear Figures | Ch-25 |myhelper

OPEN IN YOUTUBE

Question 3

Sol :

Area of Upper rectangle=25×6=$150 \mathrm{~cm}^{2}$

Area of bottom rectangle=10×(19.5-6)=10×13.5=$135\mathrm{~cm}^{2}$

Area of triangle$=\frac{1}{2} \times 4 \times 8$=4×4=$16 \mathrm{~cm}^{2}$

Total Area =150+135+16=$301 \mathrm{~cm}^{2}$

---

Q4 | Ex-25E | Class 8 | S.Chand | Composite maths| Areas of Rectilinear Figures | Ch-25 |myhelper

OPEN IN YOUTUBE

Question 4

Sol :

Area of rectangle=l×b=6×3=18 cm²

Area of triangle$=\frac{1}{2} \times b \times h$

$=\frac{1}{2} \times 1 \times 1$

=0.5 cm²

Total Area = Area of rectangle-Area of triangle
=18-0.5=17.5 cm²

---

Q5 | Ex-25E | Class 8 | S.Chand | Composite maths| Areas of Rectilinear Figures | Ch-25 |myhelper

OPEN IN YOUTUBE

Question 5

A school crossing sign has the dimensions as shown in the figure.

(i) What is the area of the sign boards ?
(ii) If the 4 such sign boards are cut from the rectangular metal sheet 350cm long and 320cm wide, what will be the area of the metal-leftover ?

Sol :

(i)

=Area of rectangle+Area of Δ

$=l \times b+\frac{1}{2} \times b \times h$

$=76 \times 38+\frac{1}{2} \times 76 \times(76-38)$

=76×38+38×38

=2888+1444=4332 cm²

(ii)

Area of metal sheet=350×320 cm²

=112000 cm²

=112000-4×(Area of sign board)

=112000-4×4332

=112000-17328

=94672 cm²