TRIGONOMETRIC RATIO
Trigonometric ratios relate the angles and sides of a right-angled triangle. The three primary ratios are sine (sin), cosine (cos), and tangent (tan), defined as sin = opposite/hypotenuse, cos = adjacent/hypotenuse, and tan = opposite/adjacent. The reciprocal ratios are cosecant (csc), secant (sec), and cotangent (cot), where csc = 1/sin, sec = 1/cos, and cot = 1/tan. These ratios are useful in solving problems involving angles and distances in geometry, physics, and engineering.