Respostas

2014-04-15T10:16:03-03:00
Use a lei dos cossenos : a² = b² + c² - 2bc.cos A
a² = 5² + 7² - 2*5*7*(3/5) (é 3/5 o cosseno ??)
a² = 25 + 49 - 42
a² = 32 ==> a = 4√2 cm (resp)