Recall that the unit vector directed from point a to point b is the position vector from a to b divided by the distance between a and b.

The three direction angles of a vector are the angles between the x-, y- and z-axes to the vector at the vector’s base.  Recall from lecture how these directions are found from a unit vector.

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Recall that the unit vector directed from point a to point b is the position vector from a to b divided by the distance between a and b.

The three direction angles of a vector are the angles between the x-, y- and z-axes to the vector at the vector’s base.  Recall from lecture how these directions are found from a unit vector.

Any questions? If so, ask here.

Recall from lecture how projections can be found using dot products. For Part a), you need to find F_AB as a vector, along with the unit vector that points along the cable AD, u_AD. The projection of F_AB onto the direction of AB is found using the dot product of  with the unit vector u_AD.

The dot product operation can also be used to find the cosine of the angle between two vectors.

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Again, recall the relationships between dot products and projections, as well as how the dot product of two vectors can be used to find the angle between those two vectors.

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