Cosecant is the reciprocal of Sine.[br]This means that: [math]cosec\alpha=\frac{1}{sin\alpha}=\frac{Hypotenuse}{Opposite}[/math]

Secant is the reciprocal of Cosine.[br]This means that: [math]sec\alpha=\frac{1}{cos\alpha}=\frac{Hypotenuse}{Adjacent}[/math]

Cotangent is the reciprocal of Tangent.[br]This means that: [math]cot\alpha=\frac{1}{tan\alpha}=\frac{cos\alpha}{sin\alpha}=\frac{Adjancent}{Opposite}[/math]

These 3 ratios are just the reciprocals of the basic trig ratios.