The cotangent is the reciprocal of the tangent, so simply calculate, on your scientific calculator, 1 / tan(68).
I believe that that isn't possible unless you have it ported to ti84 or you know how to. the file format is different, and the game is built for a separate calc.
For any calculator Sec(Secant) = 1/Cos Csc (Cosecant) = 1/ Sin Cot (Cotangent) = 1/Tan
Short answer; you can't. But you can purchase (or borrow) a TI84 calculator and use the TI83's transfer cable to transfer data from the 83 to the 84 to your mac computer (the TI84 comes with a USB transfer cable).
On my graphing calculator, a TI84 Plus, I can enter the equation into the Y= (a button) and then graph it by hitting the Graph button.
Either press the carat button followed by a 3 or go to the math function and select cubed.
Cotangent is a trigonometric function. It is the reciprocal of the tangent.
The cotangent of 510 degrees is: -1.73205081
Cotangent(0.675 radians) = 84.88 approx.
Cotangent of ∞ is not π/2. It's actually nonexistent since cotangent is the continually oscillating function.
The answer is undefined as the Cotangent of Pi is undefined.
One cannot actually purchase cotangent, as it is not a service or a product. Cotangent is actually a trigonometric function comparing the angles of right triangles.