If <3 is congruent to <4,prove that <3 and <4 are right angles.
LOL, without a drawing there is no way. Perhaps they add up to a straight line?
Yes they do add up to a straight line with a bisector making each angle equal to 90 degrees
well then 90 degrees is 1/4 circle, straight line is 1/2
1/4 = 1/2 of 1/2