Now etch a line on the ruler from opposite the central disc point to its periphery so that it is 17°, or whatever you may desire, obliquely to the west side of the rule's longitudinal lines.
Ngoku krwela umgca kwirula kwisiphelo ukwenzela ukuba iqondo elingu17°, okanye nobayintoni ozakuthi uyinqwenele kwicala lase Ntshona elide lemigca yerula