 Take a minute and sketch this in your notes. We need to find angles 1, 2, and 3. So to find angle 1, first recognize that angle 1 and this adjacent angle 57 degrees form a linear pair. So linear pairs are supplementary, so that means angle 1 must be 123 degrees because 123 plus 57 makes 180 degrees. Next take a look at this red triangle. In that triangle, we know two of the three angles. We know 57 degrees, 71 degrees, and angle 2 is unknown. According to the triangle sum theorem, those three angles together add up to 180 degrees. So we can solve for angle 2 by adding the two angles together and then solving for the third. Solving for angle 2 gives you 52 degrees, and then we'll solve for angle 3 in a similar way. Let's take a look at this green triangle up top. Once again, according to the triangle sum theorem, angle 3 plus 123 degrees, which was angle 1, plus 28 degrees, should add up to 180 degrees. Which means the measure of angle 3 is 29 degrees.