If Sin0=3/5, then cos0=?

Apex

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