An area measured on a plan with the help of a planimeter was found to be 30 sq. cm. Find the true area of the field if the plan is drawn to a scale of 1 cm = 7 m.

A contouring of a reservoir site was surveyed and the following data was found: Contour (m) : Area enclosed (hectares)620 : 23625 : 112630 : 425635 : 910640 : 1200 Calculate the total volume of water impounded using the Prismoidal formula.

A fore bearing angle in a whole circle bearing (WCB) system was measured as 165°. What is the relation used to find the back bearing angle of the line?