Question

Does anyone can help me to prove this too?? Thank you before ....

Answer 1

$\frac{1}{ cos^{2} \alpha } + \frac{1}{ sin^{2} \alpha } = \frac{ sin^{2} \alpha + cos^{2} \alpha }{ sin^{2} \alpha * cos^{2} \alpha } = \frac{1}{sin^{2} \alpha * cos^{2} \alpha}$