Question

If students only know the radius of a circle, what other measures could they determine? Explain how students would use the radius to find the other parts.

Answer 1

Radius of the circle : Radius is the distance from the center outwards.

With the help of radius we can determine the following terms:

1. Diameter : Diameter is the twice of radius and it is teh staright line that passes through the center. Expression for the diameter is :

`\text{ Diameter= 2}* Radius`

2. Circumference: Circumference of the circle or perimeter of the circle is the measurement of the boundary of the circle. It express as:

`\begin{gathered} \text{ Circumference of Circle=2}\Pi(Radius) \\ \text{ where }\Pi=3.14 \end{gathered}`

3. Area of Circle: Area of a circle is the region occupied by the circle in a two-dimensional plane. It express as:

`\begin{gathered} \text{ Area of Circle = }\Pi(radius)^2 \\ \text{where : }\Pi=3.14 \end{gathered}`

4. Center Angle of the Sector: Central angles are subtended by an arc between those two points, and the arc length is the central angle of a circle of radius one. It express as :

`\text{ Central Angle of sector=}\frac{Area\text{ of Sector}}{\Pi(radius)^2}*360`

5. Arc length : An arc of a circle is any portion of the circumference of a circle. It express as :

`\text{ Arc Length = }Radius(\text{ Angle Substended by the arc from the centerof crircle)}`

In the given figure the radius is AO & BO