a) ABD and CBD are Supplementary angles and need to equal 180 degrees
Subtract 117 from 180 for CBD:
CBD = 180 - 117 = 63 degrees
b) In triangles the the shortest side would be opposite the shortest angle.
Since angle D is 56 degrees ( the smallest inside angle) then side BC would be the shortest side.
c) The side opposite the largest angle would be the longest.
Angle B is 63 degrees ( the largest) so side CD is the longest.