Answer:
Y ≈ 59.0°
Step-by-step explanation:
Using the Cosine Rule in Δ XYZ
cosY = [tex]\frac{x^2+z^2-y^2}{2xz}[/tex]
Here x = 22, y = 20, z = 22, then
cosY = [tex]\frac{22^2+18^2-20^2}{2(22)(18)}[/tex]
= [tex]\frac{484+324-400}{792}[/tex]
= [tex]\frac{408}{792}[/tex] , thus
Y = [tex]cos^{-1}[/tex] ( [tex]\frac{408}{792}[/tex] ) ≈ 59.0° ( to the nearest tenth )
