Question

How do find the derivative of `y = (sec)^2 x + (tan)^2 x`?

Answer 1

Assuming that secx=1/cosx we have that

`y=(1/cosx)^2+(sinx/cosx)^2=>y=(1+(sinx)^2)/(cosx)^2`

Hence the derivative is

`dy/dx=4*tanx*(1/cosx)^2`