sin(39π/2) = sin(19π + π/2) = sin(π/2) = 1cos(7π/2) = sin(3π + π/2) = sin(π/2) = 1
Therefore, sin(39π/2) - cos(7π/2) = 1 - 1 = 0
sin(39π/2) = sin(19π + π/2) = sin(π/2) = 1
cos(7π/2) = sin(3π + π/2) = sin(π/2) = 1
Therefore, sin(39π/2) - cos(7π/2) = 1 - 1 = 0