Answer:
cos A = 9/41
Explanation:
cosine is a function that puts together the ADJACENT side of a triangle in a ratio with the HYPOTENUSE.
So from angle A the side length 9 is right next to A so it is the ADJACENT side. The HYPOTENUSE is the longest side ,that is the side length 41.
so cos A = ADJ/HYP
cos A = 9/41
It could be that the directions were confusing bc they said simplest radical form. Many, but not all right triangles have one or more sidesides that have a radical as part of their measure. This triangle doesn't. If you get a radical in the denominator of a ratio, be sure to rationalize so that there is no radical on the bottom.