The original worked lessons remain the main explanations. Use these focused reminders to check the conditions before you start.
Identities, factorisation and valid domains
Prove identities using the two P1 core identities.
Keep restrictions from original denominators.
Factor equations without losing zero-factor solutions.
Use \(\sin^2x+\cos^2x=1\) and \(\displaystyle \tan x= \frac{\sin x}{\cos x}\). Start an identity proof from one side. Cancellation does not fill a hole in the original domain. Check a zero factor before dividing by it.