Question

вычислите: cos $alpha$,sin $alpha$,ctg $alpha$,если 0<$alpha$<($pi$/2) и tg $alpha$ = 2,4

Answer 1

 cos ,sin ,ctg ,если 0<<(/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