tg x=1/ctg x=1/5/12=12/5
tg x=12/5
sinx/cosx=12/5
Ridicand la patrat obtinem:
sin^2 x/cos^2 x=144/25
Pe sin^2 x il putem scrie ca 1-cos^2 x:
1-cos^2/cos^2x=144/25
1/cos^2 x- cos^2x/cos^2x=144/25
1/cos^2 x - 1=144/25
1/cos^2 x=144/25+1
1/cos^2 x=169/25
169cos^2 x=25
cos^2 x=25/169
cos x=5/13
sin^2 x=1-cos^2x
sin^2 x=1-25/169
sin^2 x=144/169
sin x=12/13
