How do I do this physics questions?
Determine the magnitude of the vector sum of the displacements Δd1 = 5.5 m [85.7° S of W], Δd2 = 20.0 m [S] and Δd3 = 29.1 m [39.2° S of E].
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answers:
electron1 say: Vector 1 has a south and west component.
South = 5.5 * sin 85.7 ≈ 5.48 meters
West = 5.5 * cos 85.7 ≈ 0.41 meter

Vector 3 has a south and east component.
South = 29.1 * sin 39.2 ≈ 18.4 N
East = 29.1 * cos 39.2 ≈ 22.6 N

Total south = 5.5 * sin 85.7 + 29.1 * sin 39.2 + 20
This is approximately 44 meters.

East = 29.1 * cos 39.2 – 5.5 * cos 85.7
This is approximately 22 N.

Displacement = √[(5.5 * sin 85.7 + 29.1 * sin 39.2 + 20)^2 + (29.1 * cos 39.2 – 5.5 * cos 85.7)^2]

This is approximately 49 meters. I hope this is helpful for you.
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oubaas say: along x axis
Δdx = -5.5*cos 85.7+29*cos 39.2 = 22.06
along y axis
Δdy = -(5.5*sin 85.7+20+29*sin 39.2) = -43.81

Δd = √Δdx^2+Δdy^2 = √22.06^2+43.81^2 = 49.05
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