Tranlate of the following statement into an equations:
The diameter (d) of a circle is twice its radius ( r ) .

The diameter of a circle is 14cm, find its radius.

. The diameter of a circle is 15cm. Find its radius.

Tranlate of the following statement into an equations: The perimeter (p) of an equilateral triangle is three times of its side (a).

Tranlate of the following statement into an equations: The selling price (s) of an item is equal to the sum of the cost price ( c ) of an item and the profit (p) earned.

If the diameter of a circle is d, then its perimeter is

Tranlate of the following statement into an equations: Amount (A) is equal to the sum of Principal (P) and Interest (I).

3. The diameter of a circle is 21 cm. Find the length of its radius.

If diameter of a circle is r cm, then the area of a circle is :

If diameter of a circle is 2r cm, then area of the circle is :

The diameter of a circle is a line which joins two points on the circle and also passes through the centre of the circle. (In the adjoining figure, AB is a diameter of the circle, C is its centre.) Express the diameter of the circle (d) in terms of its radius (r).