The discussion explores the derivation of trigonometric identities, specifically focusing on whether the formula for tan(2a) can be derived from simpler formulas, similar to how sin(2a) and cos(2a) can be derived from Euler's identity. Participants suggest using the addition formula for tangent, which states that tan(A+B) = (tan(A) + tan(B)) / (1 - tan(A)tan(B)), as a straightforward method. Another approach discussed involves expressing tan(2a) as sin(2a)/cos(2a) and manipulating it using known values for sin(2a) and cos(2a). The conversation also touches on geometric methods for deriving sine addition formulas. Overall, the thread emphasizes the connections between different trigonometric identities and their derivations.