There are six possible side ratios named: Sine, Cosine, Tangent, Cosecant, Secant, and Cotangent.

The Pythagorean theorem applies,
Special 30-60-90 triangle:

Special 45-45-90 triangle:

Special Trig Function Values:

Pythagorean triples (primitives) with c ≤ 100:Note: (6, 8, 10) is not a primitive because it is a multiple of (3, 4, 5).

Trigonometric functions of special angles in classic table form: