area of a triangle cosine of the angle Pythagorean theorem reduction formulas sine of the angle theorem of cosines trigonometric functions
How to Cite
Vaškas , P. (2009) “Trigonometric functions in the secondary school”, Lietuvos matematikos rinkinys, 50(proc. LMS), pp. 129–133. doi:10.15388/LMR.2009.23.
In the school mathematics trigonometric functions for acute angle and obtuse angle are defined differently. The common definitions of trigonometric functions for the both cases in the paper are proposed.
