radius is the half of diameter, so radius is 28÷ 2 =14 cm.
How do you find the radius with the diameter and circumference?
Finding the Diameter or Radius The circumference of a circle is equal to pi times the diameter. The diameter is two times the radius, so the equation for the circumference of a circle using the radius is two times pi times the radius.
What is the radius of 21cm?
What is the area of a circle with radius 21 cm?
| Result: The area of a circle with radius 21 is 1385 | |
|---|---|
| Formulae: | |
| r = 21 d = 42 C = 132 | A = πr2 = π(d2)2 A = C24π π = 3.1415 A = area C = circumference or perimeter r = radius, d = diameter |
How is the radius of a black hole determined?
A supermassive black hole has a similar radius to our solar system The radius of a black hole is determined by its mass and is called the Schwarzschild radius r_s. r_s = (2GM)/c^2 Where G is the gravitational constant, M is the mass of the black hole and c is the speed of light. The Schwarzschild radius for our Sun is only about 3km.
How is the radius of a circle calculated?
What is a Circle’s Radius? The radius of a circle is the distance from a circle’s origin or center to its edge. Conveniently, it is half as long as the diameter of a circle. A diameter is just two radiuses drawn in opposing directions from the circle’s origin.
How is the circumference of a circle related to its diameter?
The circumference of a circle is pi times its diameter. The diameter of a circle is the distance from one edge to the other, passing through the center. It is twice the radius.
How to find the area of a circle?
Area, on the other hand, is all the space contained inside the circle. It’s also straightforward to find the area if you know the radius: You can enter the radius and then compute diameter and circumference in mils, inches, feet, yards, miles, millimeters, centimeters, meters and kilometers.
