Basic Formulae
1. Sin² x + Cos² x = 1
2. 1 + tan² x = sec² x
3. 1 + cotan² x = cosec² x
Trigonometrical ratios for sum and difference
1. Sin (a+b) = sin a.cos b + cos a.sin b
2. Sin (a-b) = sin a.cos b - cos a.sin b
3. Cos (a+b) = cos a.cos b - sin...
