Your calculator might not be able to perform a "secant" function, but that's because it's easy to convert.
On top of your three basic trig functions (sine, cosine, and tangent) there are three more which act as their reciprocals. (cosecant, secant, and cotangent, respectively)
As review: A reciprocal is when you flip a fraction. For instance, the reciprocal of 2/3 is 3/2. If you have some number that's not a fraction like 5, you can put it as a fraction 5/1 and then get the reciprocal 1/5.
sec(85°) is the reciprocal of cos(85°)
sec(85°) = 1/cos(85°) = 1/0.0871557427 = 11.4737133 (round as needed)