Calculus (1 Viewer)

[abdog]

Q19. A 3m piece of wire is cut into two pieces and bent around to form a square and a circle. Find the size of the two lengths, correct to 2 decimal places, that will make the total area of the square and circle a minimum.

Please show your working. Thanks!

 

[Carrotsticks]

 

[abdog]

It does not make sense. The answers are 1.68cm and 1.32cm. I still can't get them. Help?

 

[Carrotsticks]

I may have made a calculation error above, it was quite roughly typed. However, all the steps are there.

 

[abdog]

I see. Thanks anyway. If you don't mind, can you help me with my other question? It's the one with the title "Calculus maxima minima help". PLEASE!

 

[Whicanti]

I got r=0.21 and x=0.42 as well.

However, the question is asking for the lengths of each individual piece.
So: you just sub in x and r into the length of the wire or sum of the two perimeters (P=4x+2(pi)r=3)

Length of square piece = 1.68 cm
Length of circle piece = 1.32 cm
^to 2 dp