Applications Of Derivatives Question 170
Question: If from a wire of length 36 metre a rectangle of greatest area is made, then its two adjacent sides in metre are
[MP PET 1998]
Options:
A) 6, 12
B) 9, 9
C) 10, 8
D) 13, 5
Show Answer
Answer:
Correct Answer: B
Solution:
Given $ 2(a+b)=36 $ , $ a+b=18 $ Area of rectangle $ =ab=a(18-a) $
$ A=18a-a^{2},,\therefore \frac{dA}{da}=18-2a $ Put $ \frac{dA}{da}=0 $ i.e., $ 18-2a=0\ \ \Rightarrow ,a=9;,\ b=9 $ .
BETA
