Answer:
X≈ 70.5°
Step-by-step explanation:
Using the cosine rule in Δ XYZ
cos X = [tex]\frac{y^2+z^2-x^2}{2yz}[/tex]
with x = 22, y = 20, z = 18 , then
cos X = [tex]\frac{202+18^2-22^2}{2(20)(18)}[/tex]
= [tex]\frac{400+324-484}{720}[/tex]
= [tex]\frac{240}{720}[/tex] , then
∠ X = [tex]cos^{-1}[/tex] ([tex]\frac{240}{720}[/tex] ) ≈ 70.5° ( to the nearest tenth )
