Which expression is a trinomial if degree 1?

Atriangle has sides with lengths of 10 yards, 13 yards, and 18 yards. is it a right triangle?

If a and b are the measures of two first quadrant angles and sin a = 4/9 and sin b = 2/5 find sin(a+b).

∠aed is formed inside a circle by two intersecting chords. if minor arc bd = 70 and minor arc ac = 180, what is the measure of ∠ aed? a) 45° b) 50° c) 55° d) 60°