Solve the given initial-value problem in which the input function g(x) is discontinuous. [Hint: Solve the problem on two interva
ls, and then find a solution so that y and y' are continuous at x = π/2.] y'' + 4y = g(x), y(0) = 1, y'(0) = 6, where g(x) = sin(x), 0 ≤ x ≤ π/2 0, x > π/2