Answer: The fraction d/c
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Step-by-step explanation:
Check out the attached image. I've labeled the three sides of the triangle based on the reference angle y. The opposite side is 9, the adjacent is d, and the hypotenuse is c.
How did I get those values? Well
sine = opposite/hypotenuse = 9/c
tangent = opposite/adjacent = 9/d
matching terms we see that opposite = 9, adjacent = d, hypotenuse = c
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Now we compute the ratio for cosine
cosine = adjacent/hypotenuse
cos(y) = d/c
We don't have enough info to know the numeric value of d/c