Cylinder is a surface traced by a straight line passing through a space curve and being parallel to a fixed vector (directrix)
Cylinder is a surface consisting of collection of straight lines (are also called generators) through a given curve (is also called directrix) parallel to a fixed direction (axis). We need three things to define a cylinder. 1. space curve (also called directrix) 2. axis (is also called a fixed vector, it is a fixed line) 3. generator (a moving straight line) तलको चित्रमा, १. हरियो रंगको curve नै space curve हो ( हेर्न को लागी बाँया तिर भएको Show/Hide Curve चेकबक्स मा click गर्नुहोस । २. निलो रंगको सिधा रेखा नै Axis हो ( हेर्न को लागी बाँया तिर भएको Show/Hide Axis चेकबक्स मा click गर्नुहोस । २.रातो रंगको सिधा रेखा नै generator हो ( हेर्न को लागी बाँया तिर भएको Show/Hide Generator चेकबक्स मा click गर्नुहोस । Show Cylinder generated by line मा click गरेर वा बाँया तिर भएको slider t लाई चलाएर cylinder हेर्नुहोस। यसरी हेर्दा, दाँया तिरको चित्र लाई पनि घुमाएर हेर्नुहोस । Space curve को definition change गरेर पनि graph हर्न सकिन्छ ।