Supplementary anglesTwo angles are said to be supplementary if their sum is 180o. This makes them add up to make a straight line. If you take a ruler and bring one end down on a table top, the two angles that the table top makes with the ruler (one angle on each side of the ruler) are supplementary angles. In the figure below, the two angles are supplementary because 140o + 40o = 180o, a straight line: Now, here is a problem for you:       What is the measure of angle x? = _______________ degrees. |