Chapter 7 - Applications of Trigonometric Functions - Section 7.3 The Law of Cosines - 7.3 Assess Your Understanding - Page 559: 38

$b \approx4.25$ $A \approx50.4^\circ$ $C\approx 74.6^\circ$

1. Use the Law of Cosines, we have $b=\sqrt {(4)^2+(5)^2-2(4)(5)cos55^\circ}\approx4.25$ 2. Use the Law of Cosines, we have $A=cos^{-1}(\frac{(5)^2+(4.25)^2-(4)^2}{2(5)(4.25)})\approx50.4^\circ$ 3. We have $C\approx(180-55-50.4)=74.6^\circ$