Circumference is given by the equation \(\displaystyle C=2\pi r\). We can use this equation with the given radius, 4.2, to solve for the circumference.

\(\displaystyle C=2\pi r =2(3.14)(4.2)=26.4\)

To find the circumference of a circle given the radius we must first know the equation for the circumference of a circle which is \(\displaystyle Cicumference=2r\pi\)

We then plug in the number for the radius into the equation yielding \(\displaystyle Cicumference=2(12)\pi\)

We multiply to find the value for the circumference is \(\displaystyle 24\pi\).

The answer is \(\displaystyle 24\pi\).

The formula for the area of a circle is A = πr².

We are given the area, and by substitution we know that 13π = πr².

We divide out the π and are left with 13 = r².

We take the square root of r to find that r = √13.

We find the circumference of the circle with the formula C = 2πr.

We then plug in our values to find C = 2√13π.

First you must draw the diagram. The diagonal of the rectangle is also the diameter of the circle. The diagonal is the hypotenuse of a multiple of 2 of a 3,4,5 triangle, and therefore is 10.
Circumference = π * diameter = 10π.

The shape of the garden consists of a rectangle and two semi-circles. Since they are building a fence we need to find the perimeter. The perimeter of the length of the rectangle is 24. The perimeter or circumference of the circle can be found using the equation C=2π(r), where r= the radius of the circle. Since we have two semi-circles we can find the circumference of one whole circle with a radius of 4, which would be 8π.

We first must calculate the distance between these two points. Recall that the distance formula is:√((x₂ - x₁)² + (y₂ - y₁)²)

For us, it is therefore: √((4 - 2)² + (6 - 5)²) = √((2)² + (1)²) = √(4 + 1) = √5

If d = √5, the circumference of our circle is πd, or π√5.

The formula for  the area of a circle is πr². For this particular circle, the area is 81π, so 81π = πr². Divide both sides by π and we are left with r²=81. Take the square root of both sides to find r=9. The formula for the circumference of the circle is 2πr = 2π(9) = 18π. The correct answer is 18π.

In order to find the circumference, we will use the formula \(\displaystyle C=2\pi r\).

\(\displaystyle C=2\pi r\)

\(\displaystyle C=2*\pi*3.5cm\)

\(\displaystyle \rightarrow 7 \pi cm\)

In order to find the circumference of a circle (which is the perimeter or distance around the circle), you must double the radius and multiply by pi (\(\displaystyle 2\cdot3\cdot\pi=6\pi\)).

The equation for the circumference of a circle is \(\displaystyle 2\Pi r\), so by substituting the given radius into the equation, we get \(\displaystyle 8\Pi\).