Answer:
Step-by-step explanation:
3.8
1. Use sine rule
d/sin(D) = f/sin(F) (d=EF, f=DE=3)
2. cross multiply
d=f(sin(D)/sin(F)) = 3(sin(75)/sin(50))=3.783
a₃ = 19
to find the third term substitute n = 3 into the nth term rule
a₃ = 4(3) + 7 = 12 + 7 = 19