Toolkit 36

General Solutions of Trigonometric Equations

sinα=sinβ    α=β+360k,  180β+360k,  kZ\sin\alpha=\sin\beta\;\Rightarrow\;\alpha=\beta+360k,\;180-\beta+360k,\;k\in\mathbb{Z}
cosα=cosβ    α=±β+360k,  kZ\cos\alpha=\cos\beta\;\Rightarrow\;\alpha=\pm\beta+360k,\;k\in\mathbb{Z}
tanα=tanβ    α=β+180k,  kZ\tan\alpha=\tan\beta\;\Rightarrow\;\alpha=\beta+180k,\;k\in\mathbb{Z}
cotα=cotβ    α=β+180k,  kZ\cot\alpha=\cot\beta\;\Rightarrow\;\alpha=\beta+180k,\;k\in\mathbb{Z}