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

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

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Given that, area = 10 sq cm,
perpendicular = 20 cm and base = ?
area = (base x perpendicular) / 2Correct 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
 The area of a right angled triangle is 40 sq cm. If its base is equal to 28 cm. find its height.

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Given that,
area = 40 sq cm,
base = 28 cm and
height = perpendicular = ?
Area = (base x perpendicular) / 2Correct 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
= 2^{6}/_{7} cm
 Find the perimeter of a triangle with sides equal to 6 cm, 4 cm and 5 cm.

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

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Area of parallelogram = Base x Height
= 8.06 x 2.08Correct Option: C
Area of parallelogram = Base x Height
= 8.06 x 2.08 = 16.76 cm^{2}