modo drawing a curve with polygons

1. select Tools panel -> basic -> sketch
2. select from tools properties panel sketch -> type -> lines
3. holding the left click drag on the 3d view whichever arc shape you want and press q to quit the tool
4. Being in edges mode, select all the edges of the arc. select Tools panel -> edge -> extend and click on the already selected arc. It displays directional arrows. Drag the arrow in which direction you want to extend the arc. This provides polygons to the arc. for my case I need not change action center value as the desired drag direction matches with the direction of x, y and z axes of the workplane. If the drag direction is different from workplane, changing action center -> element and right clicking on any surface displays directional lines aligned to that surface. This helps to move the selected surface relative to the direction of another surface.
5. as the arc is drawn with lines, curve might not appear really curve. if somewhere curve is looking sharp, being in edges mode select that sharp edge, then select Tools panel -> edge -> bevel, holding the left button drag on the panel so that the sharp edge becomes smooth.

if any time you want to see the vertices use ctrl+1 -> toggle vertices. As this option highlights vertices, any complex object with too many vertices get displayed as a collection of black points, with reduced clear identification of its shape. If any time you notice an item being displayed in black color, then treat it as toggle vertices option being turned on

use m key to change the color of items in different meshes. when you are drawing a line along an item, colors help in clearly distinguishing one from other.

Tools panel -> edge -> extend creates a new set of edges along with the vertices. Move those newly created edges in whatever direction you want without disturbing the already existing structure.

Any polygon has only one face, which won't be visible from backside. If you want to see it from backside, being in Polygons mode tools menu -> polygon side tab ->  commands panel -> flip, flips front to the back


i found drawing using sketch tool along a shape is difficult as sketch tool adds a new vertex wherever left button is released. I felt less comfortable. rather than the sketch tool use the vertex tool.

1. put vertices along the shape, using the Tools panel -> basic tab -> vertex tool. To see the placed vertices turn on ctrl+1 -> toggle vertices.
2. select 2 verts, hit 'p', that'll create edge 
3. Being in edges mode, select all the edges of the arc. select Tools panel -> edge -> extend and click on the already selected arc. It displays directional arrows. Drag the arrow in which direction you want to extend the arc. This provides polygons to the arc. for my case I need not change action center value as the desired drag direction matches with the direction of x, y and z axes of the workplane. If the drag direction is different from workplane, changing action center -> element and right clicking on any surface displays directional lines aligned to that surface. This helps to move the selected surface relative to the direction of another surface.