Vectors in Space
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Vectors in Space. We live in a Three Dimensional World. Rectangular Coordinates in Space. Right handed coordinate system We now have an ordered triple (x,y,z) associated with each point. Graphing examples. Representing Vectors in Space.
Vectors in Space
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Vectors in Space We live in a Three Dimensional World
Rectangular Coordinates in Space • Right handed coordinate system • We now have an ordered triple (x,y,z) associated with each point. • Graphing examples
Representing Vectors in Space • Since we have a new axes, we will now need a third unit vector to represent the z axis. • i = (1, 0, 0) j = (0, 1, 0) and • k = (0, 0, 1)
Position Vector • To find the position vector, we will now have • v = (a2 – a1)i + (b2 – b1)j + (c2 – c1)k
Addition, Subtraction and Scalar Multiplication • All rules that applied in two dimensions, now apply in three dimensions
Unit Vector in Direction of v • For any non zero vector v, the vector • is a unit vector that has the same direction as v.
Dot Product • We find the dot product the same way we found it in two dimensions, we just add the third dimension
Angle Between Two Vectors • We use the same formula we used in two dimensions including the third dimension
Direction Angles of Vectors in Space • This is the only truly new operation. • There are three direction angles • a = angle between v and the positive x-axis, 0 ≤ a ≤ p • b = angle between v and the positive y-axis, 0 ≤ b ≤ p • g = angle between v and the positive z-axis, 0 ≤ g ≤ p
Direction Cosines • The direction cosines play the same role in space as slope does in the plane.
Property of Direction Cosines • If a, b, and g are the direction angles of a nonzero vector v in space, then • cos2a + cos2b + cos2g = 1