Green’s Dictionary of Slang

trigonometry.

1896		W.C. Gore Student Sl. in Cohen (1997) 7: trig. n. Trigonometry.
1905		‘West Point Sl.’ in Howitzer (US Milit. Academy) 292–5: Trig — Trigonometry.
1924		P. Marks Plastic Age 36: When Hugh caught the word ‘trigonometry’ he actually thrilled with joy. He had had trig in high school.
1967		P. Thomas Down These Mean Streets (1970) 225: In a special exam at Howard University I had passed everything but my math, and Howard was gonna send me to Dunbar High School for a special course in trig.
1985		J. Briskin Too Much Too Soon (1986) 347: Studying trig like crazy.