Hi there!
The definition of the cosine:
[tex] \cos( \alpha ) = \frac{adjecent}{hypotenuse} [/tex]
When we fill in this formula with the data from the picture, we get the following:
[tex] \cos(d) = \frac{21}{75} = \frac{7}{25} [/tex]
Therefore, the answer is 7 / 25
