Circumference of a circle is found with the equation
C = 2 × pi × r
where r is the radius. So for your problem...
C = 2 × 3.14 × 4
C = 25.12 meters

we needed to eliminate w, do so by diving both sides by w and obtain the above result :)
Hope this helps.
Solve for
:

Now if
, we have
and

On the other hand, if
, then
and

Add all the numbers then divide by how many dates there are.
To solve using completing square method we proceed as follows:
x^2-10x+8=0
x^2-10x=-8
but
c=(b/2)^2
c=(10/2)^2=25
thus we can add this in our expression to get
x^2-10x+25=8+25
factorizing the LHS we get:
(x-5)(x-5)=33
(x-5)^2=33
getting the square roots of both sides we have:
x-5=+/-√33
x=5+/-√33