Question

Find the diameter of the circle if radius is $8.8\;cm$?

Answer 1

Hint: We can solve this if we know the definition of radius and diameter. We know a line segment having both the endpoints on the circle and the largest chord of the circle is called diameter. A line segment connecting the centre of a circle to any point on the circle itself is called radius.

Complete step by step answer:
Given, radius is \[8.8{\text{ }}cm\].
That is \[r = 8.8{\text{ }}cm\].
From the definition of diameter and radius we know that diameter is equal to two times the radius of the circle or radius is half of the diameter.
That is
\[ \Rightarrow r = \dfrac{d}{2}\]
Or
\[ \Rightarrow d = 2r\]
Now substituting the radius we have
\[ \Rightarrow d = 2 \times 8.8{\text{ }}cm\]
\[ \Rightarrow d = 17.6{\text{ }}cm\]
Hence the diameter is \[17.6{\text{ }}cm\].

Note: If they asked us to find the radius by giving diameter or by giving circumference or by giving area of circle, we can easily find the radius. If they have given diameter and asked us to find the radius then we use the formula \[r = \dfrac{d}{2}\] where ‘d’ is diameter. If they have given the circumference of a circle and asked us to find the radius of the circle then we use \[r = \dfrac{c}{{2\pi }}\] ‘c’ is the circumference of the circle. Similarly if they have given the area of the circle and asked us to find the radius then we use \[r = \sqrt {\dfrac{A}{\pi }} \] where ‘A’ is the area of the circle. We should be careful about the unit as well. Usually we represent it in meters but we can put the answer in centimeters also.