Question: Assume the complete question as, Two forces of 20 Newton’s and 30 Newton’s² act on a point. The resultant force is 40 Newton’s. Find the angle between the two forces
Answer:
75.5°
Step-by-step explanation:
From the question,
Using cosine rule,
R² = P²+Q²-2PQcosθ................... Equation 1
Where θ angle between the the two forces.
Given; R = 40 Newton, P = 20 Newton, Q = 30 Newton.
Substitute these values into 1
40² = 20²+30²-[2×20×30(cosθ)]
1600 = 400+900-(1200cosθ)
1600 = 1300-1200cosθ
1200cosθ = 1600-1300
1200cosθ = 300
cosθ = 300/1200
cosθ = 0.25
θ = cos⁻¹(0.25)
θ = 75.5°
Hence the angle between the forces is 75.5°
