emperor of Rome (284-305) who divided the Roman empire into east and west (286) in an attempt to rule the territory more effectively, appointed two rulers for each section with direct sub-rulers for each, appointed a co-emperor which lead to power struggle, army leader and the son of a slave who tried to restore order to the empire.
A right angle triangle always consists of one 90 degree angle, and every triangle must equal 180 degrees. Here is the work for this problem: 90 degrees (representing the right angle) + 50 degrees equals 140 degrees. 180 minus 140 equals 40. Therefore, the remaining angle would be 40 degrees.
This rectangle has four 90 degree angles adding up to 360 degrees. Since the triangles are congruent each triangle has half as many degrees, namely 180. So this is true for any right triangle. Suppose you triangle is not a right triangle. Draw a perpendicular from the vertex opposite the longest side, to the longest side. What you have now is two right triangles which, by the above contain 360 degrees in total. But if you look at the two right angles that add up to 180 degrees so the other angles, the angles of the original triangle, add up to 360 - 180 = 180 degrees.