Circumference of a circle - derivation
This page describes how to derive the formula for the circumference of a circle.
Recall that the definition of pi (π) is the circumference c of any circle divided by its diameter d. Put as an equation, pi is defined as
π
=
c
d
Rearranging this to solve for c we get
c
=
π
d
The diameter of a circle is twice its radius, so substituting 2r for d
c
=
2
π
r
If you know the area
Recall that the area of a circle is given by
area
=
π
r
2
Solving this for r
r
2
=
a
π
So
r
=
√
a
π
The circumference c of a circle is
c
=
2
π
r
Answer:
21x^2-2x+1
Step-by-step explanation:
The area of shaded region= The area of the floor - area of the identical islands
The area of shaded region=(5x+1)^2-2*(2x)(x+3)=25x^2+1+10x-4x^2-12x=21x^2-2x+1
Answer: The correct option is, It is a line joining the points whose x and y coordinates add up to 4.
Step-by-step explanation:
The given equation is, 
when we take x = 1 then
when we take x = 2 then
From this we conclude that the sum of 'x' and 'y' coordinates is always equal to 4.
Hence, the correct answer is, It is a line joining the points whose x and y coordinates add up to 4.
D : c = 33 : 22
where d is the number of dogs and c is the number of cats;
and: d + c = 3030
33 c = 22 d / : 11
3 c = 2 d
From the other equation: c = 3030 - d
3 * ( 3030 - d ) = 2 d
9090 - 3 d = 2 d
5 d = 9090
d = 9090 : 5
d = 1818
Answer: There are 1818 dogs in the shelter.
