2. Write the wave equation for scalar function, f. Check whether f = Asin[k(x-vt)] is a solution or not, by inserting it into the wave equation. Check whether f =Acos(kx-wt) is a solution or not, by inserting it into the wave equation. Check whether f = Acos(kx²-wt) is a solution or not, by inserting it into the wave equation.