Na figura a seguir determine o valor desconhecido considerando que sen(a)= 2/5 https://lh6.googleusercontent.com/D21f0mHWy3ATRrJyBw4xAgXUQwKzhvf5MNCyg2i1CrUyv-OHm9u12ezG_VYs6DPR6eVxFcsP00_XCHIUo2FeVTSYNmlBRbB7FAMoDREupAKJx_sYCI2vAjtsJCFl=w740