The line that goes through the midpoint of the circle and cuts it into two equal halves is called the diameter (d) (the black line).
You diameter is 14cm long and to find the area of circle you need radius (r).
[tex]d=14\mathrm{cm}[/tex]
Radius is defined as d/2 (a half of diameter).
[tex]r=\dfrac{d}{2}=\dfrac{14\mathrm{cm}}{2}=7\mathrm{cm}[/tex]
Now that we know the radius we can calculate area
[tex]A=\pi r^2\approx3.14\cdot(7\mathrm{cm})^2\approx\boxed{153.86\mathrm{cm^2}}[/tex]
Hope this helps.
