I did a) in a different way than you did (to be exact you should use probably absolute values)
would i have to state i am approximating cos(x) with a/b. since there are values for cos(x) that are irrational and can't be written as a rational function
would i have to state i am approximating cos(x) with a/b. since there are values for cos(x) that are irrational and can't be written as a rational function
In his example, earboth stated that a and b are elements of irrational numbers.