4 times pi times 4 divided by 2 is 78.9568352087
4
12
28
2 x pi x 2 = 4 x pi
A = C^2/(4 pi) The area of the circle is... The circumference squared... divided by 4... divided by pi If you already know the area, then you can multiply it by 4*pi, and then the square root of the product is equal to the circumference! C = (A*(4 pi))^(1/2)
As tan(x)=sin(x)/cos(x) and sin(pi/4) = cos(pi/4) (= sqrt(2)/2) then tan(pi/4) = 1
2
It is: pi*4^2 divided by 2 = 8/pi which is about 25 square cm
0.75
6
1.00000000075
The answer depends on what the question is!