Verify the identity.

cos(x)/(1+sin(x)) =sec(x)-tan(x)

OK, on the right side we have

1/cos(x) - sin(x)/cos(x)

(1 - sin(x)) /  cos(x)    Multiply numerator and denominator by cos(x)

[(cos(x)* (1- sin(x)] / [cos²(x)]

[(cos(x)* (1- sin(x)]/ (1 - sin²(x))

[(cos(x)* (1- sin(x)]/ [(1 + sin(x)) * (1 - sin(x)]

cos(x)/(1+sin(x))   which equals the left hand side

I don't know what the identity is but the answer is tan_rad(((pi*x)/180))=-sin_rad(((pi*x)/180))sec(((pi*x)/180))-cos_rad(((pi*x)/180))