упростить выражение) помогите решить
Sina/(1-cosa) + sina/(1+cosa)=(sin(1+cosa)+sina(1-cosa))/(1-cos^a)=2sina/sin^2a=2/sina
![=sina\bigg({{1}\over{1+cosa}}+\frac{1}{1-cosa}\bigg)=\\=sina\bigg[(1-cosa+1+cosa)/((1+cosa)(1-cosa))\bigg]=\\=sina*2/(1-cos^2 a)=\\=sina*2/sin^2a=2/sina](https://tex.z-dn.net/?f=+%3Dsina%5Cbigg%28%7B%7B1%7D%5Cover%7B1%2Bcosa%7D%7D%2B%5Cfrac%7B1%7D%7B1-cosa%7D%5Cbigg%29%3D%5C%5C%3Dsina%5Cbigg%5B%281-cosa%2B1%2Bcosa%29%2F%28%281%2Bcosa%29%281-cosa%29%29%5Cbigg%5D%3D%5C%5C%3Dsina%2A2%2F%281-cos%5E2+a%29%3D%5C%5C%3Dsina%2A2%2Fsin%5E2a%3D2%2Fsina+ "=sina\bigg({{1}\over{1+cosa}}+\frac{1}{1-cosa}\bigg)=\\=sina\bigg[(1-cosa+1+cosa)/((1+cosa)(1-cosa))\bigg]=\\=sina*2/(1-cos^2 a)=\\=sina*2/sin^2a=2/sina")