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Roxyyonela
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Ajutor.! :
In triunghi ABC se considera inaltimea AD _|_ BC , D apartine BC . Stiind ca AD=12cm , cosC= 5 supra 13 si sin B= 3 supra 5 , calculati lungimea laturi [BC].

Răspuns :

Renatemambouko
cos  C=5/13
cos C=DC/AC
AC=13k
DC=5k
AD²=AC²-DC²
144=169k²-25k²
144k²=144
k=1
AC=13
DC=5
sin B=AD/AB
3/5=12/AB
AB=12*5/3=20
BD=√(20²-12²)=√(400-144)=√256=16
BC=16+5=21

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