Answer:
a ≈ 7.14
Explanation:
The mnemonic SOH CAH TOA reminds you of the relations between angles and sides. The one relevant here is the one that involves the opposite side (5) and the adjacent side (a) for the angle marked 35°.
Tan = Opposite/Adjacent
tan(35°) = 5/a
a = 5/tan(35°) ≈ 5/0.700208
a ≈ 7.14