# Identities in Trigonometry

### A right angled triangle has a hypotenuse,
base and the perpendicular side. Let angle A be the angle
between the base and the hypotenuse.

### then

### Sin A = perpendicular / hypotenuse

### Sin A = perpendicular / hypotenuse

### Tan A = (Sin A) / (Cos A) = perpendicular /
base

Sec A = 1 / Cos A
### Cot A = 1 / Tan A = (Cos A) / (Sin A)

### Cosec A = 1/ Sin A

### Certain basic Trignometry identities
applicable to any angle are:

### Sin (-A) = - Sin A

### Cos (-A) = Cos A

### Tan (-A) = - Tan A

### Sin^{2}A + Cos^{2}A = 1

### 1 + Tan^{2}A = Sec^{2}A

### 1 + Cot^{2}A = Cosec^{2}A