what are oblique sketch.

We can draw the cube on a plain paper as follows:

(i) Since the back edges of the cube are not visible, they are joined using dotted lines. By convention, the hidden edges have to be shown by doted lines.

(ii) Here, we can see that all line segments are not equal (in measurement), yet they seem to be equal in the figure and we can easily recognize it as a cube.

These sketches are known as oblique sketches.