What is the greatest number of right angles that a triangle can contain?

1. a right angle is 90 and every triangle has angles totaling 180.

triangles also need 3 angles and if you have 2 right angle they = 180 and there is no 3rd angle to make it a triangle.

  We first have to know that all triangle equal 180 degrees, and we have to know that all right angles equal 90 degrees as well. now that we know that information we can now continue.  for a right triangle we know right off the bat that is has a 90 degree angle, and that it must equal 180 degrees, and if you subtract 90 from 180 you are left with 90 again, But, we cant have all three angles equal to 90 because then that gives us 270 degrees and that violates our rule that all triangles equal 180. So what we do is divide 90 by 2 to give us 45 for the last two angles, and if you add 45 + 45 + 90 our answer is 180 meaning our largest angle is 90

so your final answer is 1 right angle because, any more and you would violate the all triangles equal 180 :