Mathematics - Trigonometric Equation Question with Solution | TestHub

$\frac{1-\cos \alpha +\sin \alpha }{1+\sin \alpha }$ $=\frac{1-\cos \alpha +\sin \alpha }{1+\sin \alpha }\cdot \frac{1+\cos \alpha +\sin \alpha }{1+\cos \alpha +\sin \alpha }$ $=\frac{(1+\sin \alpha {)}^2-{\cos }^2\alpha }{(1+\sin \alpha )(1+\cos \alpha +\sin \alpha )}$ $=\frac{\left(1+{\sin }^2\alpha +2\sin \alpha \right)-\left(1-{\sin }^2\alpha \right)}{(1+\sin \alpha )(1+\cos \alpha +\sin \alpha )}$ $=\frac{2\sin \alpha }{1+\cos \alpha +\sin \alpha }=y$