What is the derivative of ##1+tan^2x##?

##2tanxsec^2x##

differentiate using the##color(blue)(” chain rule “) ##

rewrite ## tan^2x = (tanx)^2##

##d/dx[ 1 + (tanx)^2] = 2(tanx) d/dx(tanx) ##

## = 2tanxsec^2x ##

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