Trigonometric functions of $\\left( {{90}^{\\circ }}+\\theta \\right)$ and $\\left( 180-\\theta \\right)$ and $\\left( 180+\\theta \\right)$.
The Cosine Waveform
trigonometry - converting cos to sin and tan in specific quadrants - Mathematics Stack Exchange
How to write cosine equation as sine function
How to Convert an Equation Written in Polar Form to Rectangular Form Involving the Trigonometric Identities Sin, Cosine or Tangent | Trigonometry | Study.com