[m]\frac{7sin(17^o)cos(17^o)}{sin(34^o)} = \frac{\frac{7}{2}2sin(17^o)cos(17^o)}{sin(34^o)} = \frac{\frac{7}{2}sin(34^o)}{sin(34^o)} = \frac{7}{2}[/m]
sin2 α =2sin α *cos α
sin34 ° =2sin17 ° *cos17 °
[m]\frac{7sin17^{o}\cdot cos17^{o}}{sin34^{o}}=\frac{7sin17^{o}\cdot cos17^{o}}{2sin17^{o}\cdot cos17^{o}}=\frac{7}{2}[/m]
О т в е т.[m]\frac{7}{2}[/m]