Find the volume of a sphere whose surface area is 1386 m².

Surface area of the sphere = 1386 m²

For sphere;

Surface Area = $$4\pi r^2$$​​

Volume = $$\frac{4}{3} \pi r^3$$​​

where r is the radius of the sphere. 

Solution: 

Surface Area of sphere = $$4 \pi r^2$$ 

​$$1386 = 4 \pi r^2 \\ 1386 = 4 \times \frac{22}{7} \times r^2 \\ \ \\ \implies r^2 = \frac{1386 \times 7}{22 \times 4} \\ \ \\ r = \frac{21}{2}$$   

Now ,

Volume = $$\frac{4}{3} \pi r^3$$ 

 $$= \frac{4}{3} \times \frac{22}{7} \times \left( \frac{21}{2} \right)^3 \\ = 4851$$ 

Thus, the volume of the sphere is 4851 m³.