Question 8: The circumference of the bottom of the cone is the arc length of the semicircle, and the radius of the semicircle is the inclined height h of the cone.

Arc length of semicircle =πh

Radius of cone bottom =h/2

Bottom area: π×(h/2)? =πh？ /4

Lateral area: πh? /2

So the ratio of lateral area to bottom area is 2: 1.

Question 7: The circumference of the cylinder is 10, and the radius R= 10/2∏.

Bottom area =∏XRXR=25/∏.

So the volume is 25/∏X 10=250/∏ (square centimeter).