use the concept of the phasor to combine the following sinusoidal functions into a single trigonometric expression

9.11 Use the concept of the phasor to combine the following sinusoidal functions into a single trigonometric expression: Round 2 decimal places a) y = 50cos(500t + 60) + 100cos(500t - 30%) a) y = b) y = 200cos(377t + 50) - 100sin(377t + 150) b) y = c) y = 80cos(100t + 30) - 100sin(100t - 135) + 50cos(100t - 90) c) y = d) y = 250cos(wt) + 250cos(wt + 120) + 250cos(wt - 120) d) y =