Given the function f (x) = - SiNx + SiNx + A, the square above that SiNx, if f (x) = O has a real number solution to find the range of a, if x belongs to R 1 (less than or equal to FX) less than or equal to ten fourths Help solve it

Given the function f (x) = - SiNx + SiNx + A, the square above that SiNx, if f (x) = O has a real number solution to find the range of a, if x belongs to R 1 (less than or equal to FX) less than or equal to ten fourths Help solve it

It seems that your problem is wrong, so I can't solve it. But the general method of this kind of problem is to separate variables, that is, express a with X, replace the equation f (x) = O with the system of equations of y = a, y = g (x) (G (x) is used to express a), and calculate the range of G (x)
If f (x) = 0 has a real solution, the range of a is the range
You seem to have a second question, but you haven't typed it out