The formula for the volume of a quarter-sphere is simply one-fourth of the volume of the sphere. So the volume of a quarter-sphere:
V = (1/4) (4/3) (π r³)
or
V = (1/3) (π r³)
Since we are given with the radius of 70 feet, the volume is
V = (1/3) (π) (70³)
V = 359,189 cubic feet
The surface area of hemisphere is given by:

Where r is radius of hemisphere.
We are given diameter = 250 ft.
We know that radius = half of diameter.
Radius of dome = 1/2 (250) = 125 ft.
Now let us plug the value of radius in the formula,

Surface Area of dome = 98125 square foot.
The product of the lengths of the parts of the chord is equal to the product of the lengths of the parts of the chord that divides it.
(7 cm)*(8 cm) = n*(4 cm)
(7*8 cm²)/(4 cm) = n
14 cm = n
16b^6 sqrt 6a would be the answer