Subash,

I would first convert the measurements to centimeters (170 cm and 190 cm). Next find the volume using the fact that the volume of a right circular cylinder is π r² h where r is the radius and h is the height. This gives the volume in cubic centimeters. But one cubic centimeter is a milliliter so you can easily convert the volume to liters. Finally to convert the volume to gallons you need to decide which gallon to use. I used Wikipedia to look up gallon and found the number of liters in an Imperial gallon and a standard US gallon. There is a table near the bottom of the page.

Harley