cot (2pi+x) = cot x

This is because after a complete revolution the values of all trigonometric ratios repeat themselves.

FOR EG:

cos 390 = cos ( 360 + 30 )

= cos 30

also the ratio does not transform after repetition of integral values of pi that is pi and 2 pi.

but they do transform after non integral values of pi like pi/2 and 3pi/2.

FOR EG:

cos (pi/2 + x) = -sin x (cos is negative in second quadrant ) ------ 1

cos (pi/2 - x) = sin x ------- 2

cos (pi - x) = - cos x -------3 ( both 1 and 3 lie in the same quadrant but notice the difference )

cos (pi + x) = - cos x

similarly this can be followed foe 3pi/2 and 2pi also.

HOPE IT HELPED !!!

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