Mathematics: A piece of wire 40 cm long is to be cut into two pieces. One piece will be bent to form a circle and; the other will be bent to form a square. Find the lengths of the two pieces that cause the sum of the area of the circle and the area of the square to be a minimum. The perimeter of the square is cm The circumference of the circle is cm

Cantorville used more kilowatt-hours than JacobiaStep-by-step explanation:...

A piece of wire 40 cm long is to be cut into two

nell1234565

21.01.2022

The perimeter of circle = 17.6 cmPerimeter of square = 22.4 cm

Step-by-step explanation:

The total length of the wire = 40 cm

Let us assume the circumference of the circle = k cm

So, the circumference of the square = ( 40 - k) cm

Now,as circumference of circle = 2πR

⇒2πR = k cm or, R = $(\frac{k}{2\pi})$

Area of the circle = πR²

or, A = $\pi (\frac{k}{2\pi} )^2$

$= \pi \times (\frac{k^2}{(2\pi)^2} ) = \frac{k^2}{4 \pi} \\\implies A = \frac{k^2}{4 \pi}$ ....... (1)

Similarly , perimeter of square = 4 x Side

⇒ 4 x Side = ( 40 - k) cm ⇒ S = $(\frac{40 - k}{4} )$

Area of the square = (Side)² = $(\frac{40 - k}{4} ) ^2$

Solving, we get: $A = \frac{1600 + k^2 - 80 k}{16}$ ....... (1)

So, combining (1) and (2), total area A is

$A = (\frac{k^2}{4 \pi} ) + \frac{k^2 + 1600 - 80 k }{16}$

or, we get: A = 0.07962 k² + 0.0625 k² + 100 - 5 k

A = 0.1422 k² - 5 k + 100

For axis of symmetry : $k = (\frac{-b}{2a} ) = (-\frac{-5}{2(0.1420}) = 17.6$

⇒ k = 17.6 inches

So, the perimeter of circle = 17.6 cm

Perimeter of square = (40 - 17.6 ) = 22.4 cm

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