Respuesta :

gmany
Use trigonometric function:

[tex]\sin51^o=\dfrac{|QR|}{17}\\\\\sin51^o\approx0.7771\\\\\dfrac{|QR|}{17}=0.7771\ \ \ \ |\cdot17\\\\|QR|=13.2107\to|QR|\approx13.2\ cm[/tex]