As a detective solving the mystery of the crossword clue “Trig function”, I first started thinking of any word related to trigonometry. Trigonometry is a branch of mathematics that deals with the relationships between the sides and angles of triangles. As such, I immediately thought of the three primary trig functions: sine, cosine, and tangent. I noticed that the space provided for the answer had six letters, which ensured that my focus was narrowed down to two words- ‘Sine‘ and ‘Cosine‘. However, I knew that the clue provided would not have been as straightforward if the answer was indeed sine. I therefore proceeded to think of other characteristics that could help distinguish between the two. After a moment of thought, it hit me- the clue needed a function that would compute the ratio of the adjacent side to the hypotenuse in a right-angle triangle. As such, given that cosine represents exactly this, I then confidently filled it in as the answer- ‘COSINE‘.