Step-by-step explanation
As we already known, the cosine in a right triangle is the length of the segment adjacent to the angle and divided by the hypotenuse.
In this case, the length of the largest side is 80 and the length of the hypotenuse is 89.
In conclusion, the ratio of the Cosine of Y is = 80 / 89 = 80 : 89 = 0.89