Chapter 11 Perimeter and Area Exercise 11.2
Question 1.
Find the area of each of the following parallelograms:
Solution:
(a) Area of the parallelogram
= base × altitude = 7 cm × 4 cm
= 28 cm^{2}
(b) Area of the parallelogram
= base × altitude = 5 cm × 3 cm
= 15 cm^{2}
(c) Area of the parallelogram
= base × altitude = 2.5 cm × 3.5 cm
= 8.75 cm^{2}
(d) Area of the parallelogram
= base × altitude = 5 cm × 4.8 cm
= 24.0 cm^{2}
(e) Area of the parallelogram
= base × altitude = 2 cm × 4.4 cm
= 8.8 cm^{2}
Question 2.
Find the area of each of the following triangles:
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Question 3.
Find the missing values:
S.No. | Base | Height | Area of the parallelogram |
(a) | 20 cm | 246 cm^{2} | |
(6) | 15 cm | 154.5 cm^{2} | |
(c) | 8.4 cm | 48.72 cm^{2} | |
(d) | 15.6 | 16.38 cm^{2} |
Solution:
(a) Area of the parallelogram =b × h
246 = 20 × h
(b) Area of the parallelogram = b × h
154.5 = b × 15
(c) Area of the parallelogram = b × h
48.72 = b × 8.4
(d) Area of the parallelogram = b × h
16.38 = 15.6 × h
Question 4.
Find the missing values:
Base | Height | Area of the triangle |
15 cm | — | 87 cm^{2} |
— | 31.4 mm | 1256 mm^{2} |
22 cm | — | 170.5 cm^{2} |
Question 5.
PQRS is a parallelogram. QM is the height of Q to SR and QN is the height from Q to PS. If SR = 12 cm and QM = 7.6 cm. Find:
(a) the area of the parallelogram PQRS
(b) QN, if PS = 8 cm
Solution:
(a) Area of the parallelogram PQRS
= SR × QM (∵ Area = Base × Height)
= 12 cm × 7.6 cm
= 91.2 cm^{2}
(b) Area of the parallelogram PQRS
Question 7.
∆ABC is right angled at A. AD is perpendicular to BC. If AB = 5 cm, BC = 13 cm and AC = 12 cm, find the area of ∆ABC. Also find the length of AD.
Solution:
Area of right triangle ABC