%0 Journal Article
%T Other trigonometric proofs of Pythagoras theorem
%A Nuno Luzia
%J Mathematics
%D 2015
%I arXiv
%X Only very recently a trigonometric proof of the Pythagoras theorem was given by Zimba \cite{1}, many authors thought this was not possible. In this note we give other trigonometric proofs of Pythagoras theorem by establishing, geometrically, the half-angle formula $\cos\theta=1-2\sin^2 \frac{\theta}{2}$.
%U http://arxiv.org/abs/1502.06628v1