Straight lines tangent to circles
Find the perpendicular bisector between the centres Draw arc from bisector through centres
+ = Straight lines tangent to circles Draw arc from centre through bisector circle Draw line from centre through intersection. Draw line PARALLEL through other circle. Join the intersection points Internal tangent
-= Straight lines tangent to circles External tangent Subtract large radius from small – draw arcDraw line from centre through intersection of arcsDraw line from centre of small circle PARALLEL to last lineJoin the tangent points
Straight lines tangent to circles External tangent Internal tangent End of presentation