The length of side b may be calculated through the Cosine Law. Which can be mathematically expressed as,
b² = a² + c² - 2ac(cos B)
Substituting the given values,
b² = (16 cm)² + (16 cm)² - 2(16 cm)(16 cm)(cos 85°)
b = 21.6189 cm
Thus, the value of b in two decimal places is approximately 21.62 cm.