TI-83 problem....Secant Graphs 1. The problem statement, all variables and given/known data What are the properties of: y= 2 sec(-2x + 90deg) + 3 2. Relevant equations sec (x) = (1/cos (x)) 3. The attempt at a solution I have a problem with finding the Domain of y= 2 sec(-2x + 180deg) + 3. First of all, I have to put the equation in a neater form: y= 2 [sec -2(x - 90deg)] + 3 Now, if I want to find the domain, I need to find what sec CAN'T equal. That is the vertical asymptotes. Now asymptotes can be found where the graph of the inverse of sec (which is cos) crossed the x-axis. So therefore I look at the corresponding cos function: y= 2 [cos -2(x - 90deg)] + 3 But the problem is: this cos function does NOT cross the x-axis. If it does not cross the x-axis then how can any vertical asymptotes appear? I later typed in "y= 2 (1/cos (-2x + 180deg)) + 3" into the TI-83. But it DID show vertical asymptotes. Does anyone know where these asymptotes came from???