trigonometry - Verify $\sec(2x) = (\sec^2(x))/(2-(\sec^2(x))$ - Mathematics Stack Exchan
Again, can someone give me just a hint as to how to start this identity verification? I've tried subbing in the all 3 cos double angle identities to the left side, but it keeps ending up back at the ... First, $\sec 2x=\frac{1}{\cos 2x}$. Writ...