2. - (1 - cosA) (1 + secA) cotA = senA
(1 - cosA)(1 + <img src="https://tex.z-dn.net/?f=%20%5Cfrac%7B1%7D%7BcosA%7D%29%28%20%5Cfrac%7BcosA%7D%7BsenA%7D%29%3DsenA%0A%20%20%20" />
<img src="https://tex.z-dn.net/?f=%20%281-cosA%29%28%5Cfrac%7BcosA%2B1%7D%7BcosA%7D%29%28%20%20%5Cfrac%7BcosA%7D%7BsenA%7D%29%3DsenA%0A%20" />
Simplificamos cosA con CosA
<img src="https://tex.z-dn.net/?f=%281-cosA%29%281%2BcosA%29%28%20%5Cfrac%7B1%7D%7BsenA%7D%29%0A" />
Identidad
<img src="https://tex.z-dn.net/?f=Sen%20%5E%7B2%7D%20A%2Bcos%20x%5E%7B2%7D%20A%3D1" />
<img src="https://tex.z-dn.net/?f=%281%5E%7B2%7D%20-cos%20x%5E%7B2%7D%20A%29%28%20%5Cfrac%7B1%7D%7BsenA%7D%29%3DsenA" />
<img src="https://tex.z-dn.net/?f=%20%5Cfrac%7Bsen%20x%5E%7B2%7D%20A%7D%7BsenA%7D%3DsenA" />
simplificando
SenA = SenA
3.
- tanA + cotA = cscA / cosA
<img src="https://tex.z-dn.net/?f=%20%5Cfrac%7BsenA%7D%7BcosA%7D%20%2B%20%5Cfrac%7BcosA%7D%7BSenA%7D%3D%20%5Cfrac%7BcscA%7D%7BcosA%7D%20%20" />
<img src="https://tex.z-dn.net/?f=%20%5Cfrac%7Bsen%20x%5E%7B2%7D%20A%2Bcos%20x%5E%7B2%7D%20A%7D%7BcosAsenA%7D%3D%20%5Cfrac%7BcscA%7D%7BcosA%7D%20" />
<img src="https://tex.z-dn.net/?f=%20%5Cfrac%7Bsen%20x%5E%7B2%7D%20A%2Bcos%20x%5E%7B2%7D%20A%7D%7BcosAsenA%7D%3D%20%5Cfrac%7BcscA%7D%7BsenA%7D" />
<img src="https://tex.z-dn.net/?f=%20%5Cfrac%7B1%7D%7BcosAsenA%7D%3D%20%5Cfrac%7BcscA%7D%7BsenA%7D%0A%20" />
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[img = 11]
[img = 12].