I have 2questions i couldn't figure out. Please tell me how to figure them out

find the delivertive of f^-1at the indicated value based off of the given information

Question 1

f(x)= 1/1+x², x> equal 0

f(1) = 1/2

find (f^-1)' (1/2)

Question 2

Compute the derivertive of the given function

f(t) - sec^-1(2t)