Supplementary means that the two angles, when put together, make a straight line (or 180 degree angle), so let's work this out.
A. The measure of angle 1 = the measure of angle 2: We know this is incorrect, just from looking at the picture, so let's cross that off.
B. The measure of angle 2 = the measure of angle 3: Angle 1 and angle 3 have the same measure, so since angle 2 isn't = to angle 1, angle 2 wouldn't be = to angle 3. Let's cross that off also.
C. Complementary means that the two angle put together make a 90 degree angle, but since angle three is already obtuse (more than 90 degrees), this answer is incorrect.
D. This answer is definitely correct! Angles 1 and 2 are supplementary, and angle 1 is equal to angle 3, therefore, angles two and 3 are also supplementary.
A squared plus B squared equals C squared, so what you need to do it square 5 and 7.
5 = 25
7 = 48
Then add then and square root your answer. 48 + 25 = 73. 73 square rooted equals an rounded amount of 8.6. SO the answer is D