Wednesday, March 02, 2005

Applications of Derivatives

The sum of the lengths of the hypotenuse and a side of a right triangle is given, show that the area of the triangle is maximum when the angle between them is π/3.


I'm also testing Infinite Infinity with this question and seeing what the response time is, so as to know whether it's more practical to use this website or to call up say Rungta and ask him what the solution is.

--Karan

5 Comments:

Anonymous Anonymous said...

The area is given by an Integral of the function describing the triangle. A differential of the integral function which is negative should do the trick...

10:40 PM  
Blogger Karan said...

Not helpful.

8:40 AM  
Blogger Maanick said...

let the hypotenuse be y
let the base be x

x + y = C (given)

Area A = 1/2 Base * Altitude

Altitude = (y^2 - x^2)^1/2 (Using the Pyth. Theorem)

so now basically

A^2 = [x^2(y^2 - x^2)] / 4 ....(i)

(we take Area Square to make the calculations easier.. otherwise taking only A will also do)

Now Differentiate (i) and apply Maxima Minima Concepts

you shud end up with A is Max when x = C/3.

now y = C - x
y = C - C/3
y = 2C/3

Base/Hypotenuse (Cosine)= (C/3)/(2C/3) = 1/2

Cos is 1/2 when the angle is 60 or Pi/3 . hence proved

5:59 PM  
Blogger Maanick said...

yeah before differentiating change y in terms of x and c (basically y = c-x)

6:01 PM  
Blogger Karan said...

Thanks, that's what I wanted. The full answer.

8:05 PM  

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