# What is the area of the circle?

Formula for Area of circle. The formula to find a circle’s area (radius)2 usually expressed as π ⋅ r 2 where r is the radius of a circle. The area of a circle is all the space inside a circle’s circumference.

So, what is the meaning of area of a circle?

Definitions and formulas for the radius of a circle, the diameter of a circle, the circumference (perimeter) of a circle, the area of a circle, the chord of a circle, arc and the arc length of a circle, sector and the area of the sector of a circle.

Why do we use pi to calculate the area of a circle?

Pi (π), the 16th letter of the Greek alphabet, is used to represent the most widely known mathematical constant. By definition, pi is the ratio of the circumference of a circle to its diameter. In other words, pi equals the circumference divided by the diameter (π = c/d).

How do you find the exact area of a circle?

If the object is a circle, and you know its circumference, you would divide the circumference by pi to find the diameter of the circle. Half the diameter is the radius. Square the radius and multiply by pi to find the area of the circle.

## What is the unit for the area of a circle?

Because the radius of a circle is equal to half its diameter, these equations are essentially the same. The units for area can be any unit for the measure of length squared: feet squared (ft2), meters squared (m2), centimeters squared (cm2), etc.

## Where is the circumference of a circle?

The distance around a circle on the other hand is called the circumference (c). Half of the diameter, or the distance from the midpoint to the circle border, is called the radius of the circle (r).

## What is pie in math?

Pi (π) is a mathematical constant that is the ratio of a circle’s circumference to its diameter, and is approximately equal to 3.14159. It has been represented by the Greek letter “π” since the mid-18th century, though it is also sometimes written as pi.

## How do you find the volume of a circle?

Calculate the volume of a cylinder with a length of 20cm, and whose circular end has a radius of 2.5cm. First, work out the area of one of the circular ends of the cylinder. The area of a circle is πr2 (π × radius × radius). π (pi) is approximately 3.14.

## How do you find the area?

To find the area of a rectangle multiply its height by its width. For a square you only need to find the length of one of the sides (as each side is the same length) and then multiply this by itself to find the area.

## How can you find the circumference of a circle?

How to find the circumference of a circle:

• The circumference of a circle can be found by multiplying pi ( π = 3.14 ) by the diameter of the circle.
• If a circle has a diameter of 4, its circumference is 3.14*4=12.56.
• If you know the radius, the diameter is twice as large.
• ## What is 2 pi r squared?

Circle illustration with circumference (C) in black, diameter (D) in cyan, radius (R) in red, and centre or origin (O) in magenta. Circumference = π × diameter = 2 × π × radius.

## How do you find the area of a half circle?

In the case of a circle, the formula for area, A, is A = pi * r^2, where r is the circle’s radius. Since we know that a semicircle is half of a circle, we can simply divide that equation by two to calculate the area of a semicircle. So, the formula for the area of a semicircle is A = pi * r^2/2.

## Is area squared?

Area is measured in square units such as square inches, square feet or square meters. To find the area of a rectangle, multiply the length by the width. The formula is: A = L * W where A is the area, L is the length, W is the width, and * means multiply.

## What is the formula to the circumference of a circle?

Keeping this in mind, you can write down the formula for finding the circumference of a circle given the radius: C = 2πr. In this formula, “r” represents the radius of the circle. Again, you can plug π into your calculator to get its numeral value, which is a closer approximation of 3.14.

## How do you find the surface area?

How to find the surface area of Rectangular Prisms:

• Find the area of two sides (Length*Height)*2 sides.
• Find the area of adjacent sides (Width*Height)*2 sides.
• Find the area of ends (Length*Width)*2 ends.
• Add the three areas together to find the surface area.
• Example: The surface area of a rectangular prism 5 cm long, 3 cm.
• ## How do I find the diameter of a circle if I know the area?

For an example, we have an area of 303,000 square meters.

• Divide the area (in square units) by Pi (approximately 3.14159). Example: 303,000/3.14159 = 96447.98.
• Take the square root of the result (Example: 310.56). This is the radius.
• Now double the radius to get the diameter (Example: 621.12 meters).
• ## What is the radius of the circle?

The circumference is the outside perimeter of a circle. It’s the distance around a circle. A radius can be a line from any point on the circumference to the center of the circle. If you put two radii together, edge to edge, going through the center of a circle, you would get a diameter.

## How do you measure the diameter of a circle?

The radius is the distance from the center of the circle to its edge. For example, if the radius of the circle is 4 cm, then the diameter of the circle is 4 cm x 2, or 8 cm. If you know the circumference of the circle, divide it by π to get the diameter.

## How do you find the surface area of the cylinder?

Since the label wraps once around the can, the area of the rectangle is the circumference of the circle x height or (2 r) * h. Add those two parts together and you have the formula for the surface area of a cylinder. After hitting the next button, enter your calculation in the box.

## What is the area of the sphere?

A simple calculus check reveals that the latter is the derivative of the former with respect to R. Similarly, the volume of a ball enclosed by a sphere of radius R is (4/3)*Pi*R3. And the formula for the surface area of a sphere of radius R is 4*Pi*R2.

## What is the area of a sector?

A circular sector or circle sector (symbol: ?), is the portion of a disk enclosed by two radii and an arc, where the smaller area is known as the minor sector and the larger being the major sector. A sector with the central angle of 180° is called a half-disk and is bounded by a diameter and a semicircle.

## What is the diameter if you know the circumference?

Solve the equation for the diameter of the circle, d= C/π. In this example, “d = 12 / 3.14.” or “The diameter is equal to twelve divided by 3.14.” Divide the circumference by pi to get the answer. In this case, the diameter would be 3.82 inches.

## How do you find the radius of a circle when you know the circumference?

To work on this problem, you will need the formula for finding the circumference of a circle using the diameter. Next, solve the problem by dividing both sides by 3.14. The 3.14 will cancel out on the right side of the equation, leaving . Then divide 34.54 by 3.14.

## What is the formula used to find the area of a triangle?

To find the area of a triangle, multiply the base by the height, and then divide by 2. The division by 2 comes from the fact that a parallelogram can be divided into 2 triangles. For example, in the diagram to the left, the area of each triangle is equal to one-half the area of the parallelogram.

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