C parameters for the general trig equation y = A·cos(Bθ+C)+D. C corresponds to the Phase Shift of the wave function.

Series introduction including complete video list:
TR-00: [   • TR-00: Introduction to Trigonometry S...  ]

International A level, Intl A Level, IAL, Edexcel, Pearson exam board, CIE, Cambridge exam board, P3, P2, Year 10, Class 11