i have some questions help

1.The formula for the area of a circle and the formula for the circumference of a circle.Write a formula for the area of a circle in terms of its circumference.

2. The formula for the height h of an equilateral triangle.where b is the lenght of a side . write a formula for the area of an equilateral traingle in terms of the following.

a.the lenght of a side only

b. the height only