Areas

The diagonal of a square is 4√2cm. The diagonal is another square whose area is double that of the first square is__________?

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The diagonal of a square is 4√2cm. The diagonal is another square whose area is double that of the first square is__________?

A. 8cm
B. 8√2cm
C. 16cm
D. 4√2cm

Explanation:
Area of given square = ½ x (diagonal) 2 = 16cm2
Area of new square =(2 x 16)cm2 = 32cm2
Let the diagonal of 2nd squared be D cm
Then ½ x D2 = 32
=> D2 =64
=> D = 8 cm

The area of a rectangle is 12 sq.metres and it’s length is 3 times that of it’s breadth. What is the perimeter of the rectangle?

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The area of a rectangle is 12 sq.metres and it’s length is 3 times that of it’s breadth. What is the perimeter of the rectangle?

A. 14m
B. 18m
C. 4m
D. None of these

Explanation:
Let the breadth be x metres , then it’s length = 3x metres
=>3x × x =12
=> x2= 4
=> x =2 l=6m, b =2m
=> Perimeter = 2(6+2)m = 16m

A rectangular field has dimensions 25m by 15m. Two mutually perpendicular passage of 2m width have been left in it’s central part and grass has been grown in rest of the field. The area under the grass is____________?

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A rectangular field has dimensions 25m by 15m. Two mutually perpendicular passage of 2m width have been left in it’s central part and grass has been grown in rest of the field. The area under the grass is____________?

A. 295m2
B. 299m2
C. 300m2
D. 375m2
Explanation:
Area under the grass = [(25 x 15) – {(25 x 2)+ (15 x 2) – (2 x 2)}] Sq.m
= [375 –(50 +30 -4)]Sq.m =(375 – 76)Sq.m = 299 Sq.m