# Derivative of Tan X = Sec sq. X Proof in Derivative Calculus Math

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Derivative of tan x is equal to sec square x. To find the derivative of tan x we use the first principle of derivative calculus method.In this video lesson of derivative we prove it properly. We see the graph of tan x also to learn nicely the meaning of derivative of tan X.
I hope you understand what is exactly derivative of tan x i.ee. derivative of tan x = sec square x