Răspuns :
tangenta unui unghi=cateta opusa/cateta alaturata
tg(b)=ac/ab
bc²=ab²+ac²
ac²=bc²-ab²
ac²=13²-5²
ac²=169-25
ac²-=144
ac=√144
ac=12
tg(b)=12/5
tg(b)=ac/ab
bc²=ab²+ac²
ac²=bc²-ab²
ac²=13²-5²
ac²=169-25
ac²-=144
ac=√144
ac=12
tg(b)=12/5