\(sin(\pi/2 – \alpha ) = cos\alpha\)
\(tg(\pi/2 – \alpha ) = ctg\alpha\)

\(sin(\pi/2 + \alpha ) = cos\alpha\)
\(tg(\pi/2 + \alpha ) = -ctg\alpha\)

\(sin(\pi – \alpha ) = sen\alpha\)
\(tg(\pi – \alpha ) = -tg\alpha\)

\(sin(\pi + \alpha ) = -sen\alpha\)
\(tg(\pi + \alpha ) = tg\alpha\)

\(sin(-\alpha ) = -sen\alpha\)
\(tg(-\alpha ) = -tg\alpha\)

\(cos(\pi/2 – \alpha ) = sin\alpha\)
\(cotg(\pi/2 – \alpha ) = tg\alpha\)

\(cos(\pi/2 + \alpha ) = -sin\alpha\)
\(cotg(\pi/2 + \alpha ) = -tg\alpha\)

\(cos(\pi – \alpha ) = -cos\alpha\)
\(cotg(\pi – \alpha ) = -cotg\alpha\)

\(cos(\pi + \alpha ) = -cos\alpha\)
\(cotg(\pi + \alpha ) = cotg\alpha\)

\(cos(-\alpha ) = cos\alpha\)
\(cotg(-\alpha ) = -cotg\alpha\)