Step-by-step explanation:
Start by multiplying both sides by cosα:
1 + sinα + (cos²α)/(1+sinα) = 2
sinα + (cos²α)/(1+sinα) = 1
Now multiply both sides by 1+sinα:
sinα + sin²α + cos²α = 1 + sinα
sin²α + cos²α = 1 Q.E.D.
Thats the answer and method i used