Question

sin, cos, and tan are three basic what?
trigonometric ratios
functions
triangle lengths
geometry

Explanation:

SIN (sine), COS (cosine), and TAN (tangent) are fundamental trigonometric ratios (or trigonometric functions when extended to the unit circle and beyond) in the context of right - angled triangles (and more generally in trigonometry). In a right - angled triangle, for an acute angle $\theta$:

• The sine of the angle, $\sin\theta=\frac{\text{opposite side to } \theta}{\text{hypotenuse}}$
• The cosine of the angle, $\cos\theta=\frac{\text{adjacent side to } \theta}{\text{hypotenuse}}$
• The tangent of the angle, $\tan\theta=\frac{\text{opposite side to } \theta}{\text{adjacent side to } \theta}$ (and also $\tan\theta = \frac{\sin\theta}{\cos\theta}$)

These are used to relate the angles of a right - angled triangle to the ratios of its side lengths. They are basic trigonometric ratios (or functions) that form the foundation of trigonometry, which is a sub - field of mathematics (specifically under Geometry and also as a part of Trigonometry which can be considered a sub - field or a part of Geometry/Algebra in some classifications).

Answer:

SIN (sine), COS (cosine), and TAN (tangent) are three basic trigonometric ratios (or trigonometric functions). In the context of right - angled triangles, they relate the angles of the triangle to the ratios of the lengths of its sides.