Aptitude - Area - Discussion
Discussion Forum : Area - General Questions (Q.No. 9)
9.
The diagonal of a rectangle is 41 cm and its area is 20 sq. cm. The perimeter of the rectangle must be:
Answer: Option
Explanation:
l2 + b2 = 41.
Also, lb = 20.
(l + b)2 = (l2 + b2) + 2lb = 41 + 40 = 81
(l + b) = 9.
Perimeter = 2(l + b) = 18 cm.
Discussion:
15 comments Page 2 of 2.
Abhi said:
1 decade ago
How did you took root of 41 there?
Mishi said:
1 decade ago
I can't understand this. Please someone explain this clearly?
Aparna said:
1 decade ago
What is the need to write the 40 there though that 2lb came from the formula (l+b)2?
Harsh said:
1 decade ago
L^2+b^2=41.
So how (l+b) ^2=41 become. Explain this please?
So how (l+b) ^2=41 become. Explain this please?
Hii said:
3 months ago
Solution.
As we know the perimeter of a rectangle is = 2 (l+b).
So, As we have. Area = 20m and by applying Pythagoras (l^2+b^2=41).
So, the parameters of rectangle= 2 (l+b) ^2 =4 (l^2+b^2+2lb)
= 4 (41+40)
= (81×4)
={324}.
P^2= 324.
Then P= 18m.
As we know the perimeter of a rectangle is = 2 (l+b).
So, As we have. Area = 20m and by applying Pythagoras (l^2+b^2=41).
So, the parameters of rectangle= 2 (l+b) ^2 =4 (l^2+b^2+2lb)
= 4 (41+40)
= (81×4)
={324}.
P^2= 324.
Then P= 18m.
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