## Area and Perimeter

#### Area and Perimeter

1. Find the area of a triangle whose sides measure 8 cm, 10 cm and 12 cm.

1. Given that, a = 8 cm, b = 10 cm and c = 12 cm

We know, that
s = (a + b + c)/2

Area = √s(s - a) (s - b) (s - c)

##### Correct Option: B

Given that, a = 8 cm, b = 10 cm and c = 12 cm

We know, that
s = (a + b + c)/2
= (8 + 10 + 12)/2
= 30/2 = 15 cm

∴ (s - a) = (15 - 8) = 7 cm
(s - b) = (15 - 10) = 5 cm
(s - c) = (15 - 12) = 3 cm

∴ Area = √s(s - a) (s - b) (s - c)
= √15 x 7 x 5 x 3
= √1575
= √25 x 63
= 5√63 cm

1. The area of a right angled triangle is 10 sq cm. If its perpendicular is equal to 20 cm, find its base.

1. Given that, area = 10 sq cm,
perpendicular = 20 cm and base = ?
area = (base x perpendicular) / 2

##### Correct Option: A

Given that, area = 10 sq cm,
perpendicular = 20 cm and base = ?
area = (base x Perpendicular) / 2
⇒ 10 = (base x 20) / 2
∴ base = 1 cm

1. The area of a right angled triangle is 40 sq cm. If its base is equal to 28 cm. find its height.

1. Given that,
area = 40 sq cm,
base = 28 cm and
height = perpendicular = ?

Area = (base x perpendicular) / 2

##### Correct Option: C

Given that,
area = 40 sq cm,
base = 28 cm and
height = perpendicular = ?

Area = (base x perpendicular) / 2
⇒ 40 = (28 x perpendicular) / 2
∴ perpendicular = 40/14 = 20/7
= 26/7 cm

1. Find the perimeter of a triangle with sides equal to 6 cm, 4 cm and 5 cm.

1. Given that, a = 6 cm, b = 4 cm and c = 5 cm
Required perimeter = a + b + c

##### Correct Option: D

Given that, a = 6 cm, b = 4 cm and c = 5 cm
Required perimeter = a + b + c
= 6 + 4 + 5 cm
= 15 cm

1. One side of a parallelogram is 8.06 cm and its perpendicular distance from opposite side is 2.08 cm. What is the approximate area of the parallelogram?

1. Area of parallelogram = Base x Height
= 8.06 x 2.08

##### Correct Option: C

Area of parallelogram = Base x Height
= 8.06 x 2.08 = 16.76 cm2