Protractor capability to draw lines based on angles

No, such an input method doesn't exist in Inkscape (but it is a known feature request).

What can be done currently in Inkscape:

a) Constrained drawing
When drawing paths with the pencil (freehand) or pen (bézier) tool, you can constrain a node to be at a multiple of the Rotation snap angle with respect to the previous node by holding down the Ctrl key while setting it.
The rotation snap angle can be set in 'Inkscape Preferences > Steps'. The default is 15°.
See also <http://tavmjong.free.fr/INKSCAPE/MANUAL/html/Paths-Creating.html#Paths-Bezier>
(scroll down to "Other useful things to know while using the Bezier Tool")

b) Guides as construction aides
Guides can be rotated freely, with constrains, rotated and snapped to existing segments, converted from objects and their angle can be set relatively / absolutely in the guides dialog (double-click a high-lighted guide).
Node-snapping to guides, guides intersections and guides origins works within the pencil and pen tool context (as well as the other shape tools).
If you need to draw a path or path segment at a certain angle, position a guide first and then draw the line snapping to the guide, or adjust already existing lines with the node tool, again using node-snapping to guides (and other node snapping targets).
<http://tavmjong.free.fr/INKSCAPE/MANUAL/html/Snapping.html#Snapping-Guide>
<http://tavmjong.free.fr/INKSCAPE/MANUAL/html/Snapping.html#Snapping-Objects>

c) Grids as construction aides
Depending on your use case, you might also consider defining a special grid (spacing, rectangular or isometric) for the current document (File > Document Properties > Grids) to draw lines with the same angle by snapping to gridline intersections.
<http://tavmjong.free.fr/INKSCAPE/MANUAL/html/Snapping.html#Snapping-Grid>