Question

Дано : sin a= -5/13 Найти : sin2 a , cos a , tg a , ctg

Answer 1

Sin^2(a)=25/169
cos^2(a)=1-sin^2(a)=(169-25)/169=144/169
cos(a)=12/13
сos(2a)=cos^2(a)-sin^2(a)=(144-25)/169=119/169
sin(2a)=2sin(a)cos(a)=2*(12/13)*(-5/13)=(-120/169)
tg(a)=sin(a)/cos(a)=(-5/13)/(12/13)=(-5/12)
ctg(a)=(-12/5)
a∈(-pi/2+2pi*n;-2pi+2pi*n), n∈Z