Araoye I. answered 04/08/21
conversion from degrees to radians is x° =πx/180 radians.
Note that 45 degrees =π/4 radians is a special angle, you should remember that its tangent value is 1
You can also determine the secant value by using the special triangle.
Set y(x) = tan x so a=π/4 and x=47π/180 (should see that x-a=δx=2π/180=π/90) and y'(x)= sec2 x
y(47π/180) =y(π/4)+(π/90)sec2(π/4)