**4.** A cubical block of side 7 cm is surmounted by a hemisphere. What is the greatest diameter the hemisphere can have? Find the surface area of solid.

**Solution:**

Side of cube **cm**

Hemisphere surmounts cube, the maximum diameter hemisphere can have = side of cube as shown in the figure below. Hemisphere will just touch the sides of top face of the cube from inside

Therefore, maximum diameter Hemisphere can have = **7 cm**

Radius of Hemisphere ** cm**

**Surface area of solid = Surface area of 5 Faces of cube + Surface area of Hemisphere + Surface area left uncovered on the top face of cube (shown in blue) **

((Area of Square ABCD) - Area of Inscribed Circle in square ABCD)