Answer: Yes they are right triangles
Explanation:
The square grid markers help us line up the angles to see that angle OBC is a 90 degree angle, and so is angle OB'C'. Any time a vertical and horizontal line meet up is when you have a 90 degree angle. A right triangle is one where it has a 90 degree angle (aka a right angle).
Extra info: it can be shown that triangle OBC is similar to triangle OB'C', which leads to the fact that the triangles are proportional.
