Answer:
4/5
Step-by-step explanation:
I believe you meant sin Ф = 3/5, since sin 0 = 0 (zero).
sin Ф = 3/5 = (opposite side) / (hypotenuse).
cos Ф = (adjacent side) / (hypotenuse)
Use the Pythagorean Theorem to find the length of the adjacent side:
(adj)² + (opp)² = (hyp)² becomes (adj)² = 5² - 3² = 25 - 9 = 16.
Then (adj) = +√16 = +4
and so cos Ф = (adj) / (hyp) = 4/5
