None, as far as I can see. Which, given that I cannot see any triangle, is not saying much!
oblique
An oblique line can be diagonal, sloping or slanted. It is not vertical, horizontal, parallel or perpendicular.
two diagonal lines that aren't touching
No, it will always have one.
None, as far as I can see. Which, given that I cannot see any triangle, is not saying much!
It depends on the way in which they are written. 4 and 7 clearly have horizontal and oblique lines. The number 1, in some fonts (like this one), also has both. All the rest have sections that are horizontal and those that are oblique.
oblique
Oblique
run at an oblique angle to vertical direction of the spine.
An oblique line can be diagonal, sloping or slanted. It is not vertical, horizontal, parallel or perpendicular.
diagonally between the vertical and horizontal
two diagonal lines that aren't touching
No, it will always have one.
AKMNRVWXYZ
Oblique incidence applies to rays that are incident at some angle OTHER THAN at right angles (90 degrees) to the surface on which they are incident. Vertical incidence IS at right angles.
Obviously the angle of incidence is different. The oblique rays spread their energy over a larger area of the surface than vertical (also called perpendicular or normal rays)