In ΔQRS, q = 370 cm, r = 910 cm and ∠S=31°. Find the length of s, to the nearest centimeter.
law of cosines: s^2=q^2+r^2-2qr cos S
s^2=136900+828100-673400 $\cdot$ 0.8571 ≈ 387784
sqrt387784 ≈ $\boxed{623}$
+592 
