Answer:
43.8°
Explanation:
Applying,
Cosine rule,
From the diagram attached,
x² = y²+z²-2yxcos∅.................... Equation 1
where ∅ = ∠YXZ
Given: x = 8.7 m, y = 10.4 m, z = 12.4 m
Substitute these values into equation 1
8.7² = 10.4²+12.4²-[2×10.4×12.4cos∅]
75.69 = (108.16+153.76)-(257.92cos∅)
75.69 = 261.92-257.92cos∅
collect like terms
257.92cos∅ = 261.92-75.69
257.92cos∅ = 186.23
Divide both sides by the coefficient of cos∅
cos∅ = 186.23/257.92
cos∅ = 0.722
Find the cos⁻¹ of both side.
∅ = cos⁻¹(0.7220)
∅ = 43.78°
∅ = 43.8°