Joining lines in pages for iPad

Getting 2 intersecting lines to join without overshoot or undershoot seems to be very hit and miss. I have tried a couple of suggested solutions but without success. Currently I rely on trying to extend or shorten a line at the maximum resolution possible. This works most of the time but not always. Is there a neat way of doing this or is it just a limitation of the software? In which case would I be better off trying a dedicated drawing app for iPad. Any suggestions?