Ans: The commonly used derivatives of six trigonometric functions are:
(d/dx) sin x = cos x
(d/dx) cos x = -sin x
(d/dx) tan x = sec^2 x
(d/dx) sec x = sec x tan x
(d/dx) cot x = -cosec^2 x
(d/dx) cosec x = -cosec x cot x