Вычислите: cos ,sin ,ctg ,если 0<<(/2) и tg = 2,4

Question

Вычислите: cos ,sin ,ctg ,если 0<<img src="https://tex.z-dn.net/?f=+%5Calpha+" id="TexFormula4" title=" \alpha " alt=" \alpha " align="absmiddle" class="latex-formula"><(<img src="https://tex.z-dn.net/?f=+%5Cpi+" id="TexFormula5" title=" \pi " alt=" \pi " align="absmiddle" class="latex-formula">/2) и tg = 2,4

Answer 1

 cos ,sin ,ctg ,если 0<<(<span>/2) и tg  = 2,4
ctga=1/tga=1/2.4=1/24/10=10/24=5/12
1/sin²a=1+ctg²a
1/sin²a=1+25/144=169/144
1/sina=13/12
sina=12/13
cosa=√1-sin²a=√1-144/169=5/13