Question

Докажите тождество
$1+ sin \alpha = \frac{cos \alpha +ctg \alpha }{ctg \alpha }$

Answer 1

$\frac{cos \alpha +ctg \alpha }{ctg \alpha }=\frac{cos \alpha }{ctg \alpha }+\frac{ctg \alpha }{ctg \alpha }=\frac{cos \alpha }{\frac{cos \alpha }{sin \alpha }}+1=sin \alpha +1$