Given is a Right triangle LMN with right angle at M i.e. angle M = 90 degrees.
Given are the sides LM = 15, MN = 36, and LN = 39.
It says to find cos(N) = ?
So opposite side would be LM, adjacent side would be MN, and LN is the hypotenuse.
We know about the "Soh-Cah-Toa" rule in which cosine ratio is given by :-
[tex] cos(N) = \frac{Adjacent}{Hypotenuse} \\\\
cos(N) = \frac{MN}{LN} \\\\
cos(N) = \frac{36}{39} \\\\
cos(N) = \frac{12}{13} [/tex]
Hence, final answer is [tex] cos(N) = \frac{12}{13} [/tex].