What is the trigonometric ratio for sin c

For this case we use the following definition:
 sine (x) = (C.O) / (h)
 Where,
 x: angle
 C.O: opposite leg
 h: hypotenuse
 Substituting values:
 sine (C) = (C.O) / (h)
 sine (C) = (AB) / (82)
 We look for AB by Pythagorean theorem:
 AB = root ((82) ^ 2 - (80) ^ 2)
 AB = 18
 Substituting:
 sine (C) = (18) / (82)
 Simplifying:
 sine (C) = (9) / (41)
 
 the ratio is:
 sine (C) = (9) / (41)