The dot product is simple to evaluate from Equation 7.3 when A is either perpendicular
or parallel to B. If A is perpendicular to B ( 90°), then AB 0.
(The equality AB = 0 also holds in the more trivial case when either A or B is
zero.) If vector A is parallel to vector B and the two point in the same direction
( 0), then AB AB. If vector A is parallel to vector B but the two point in opposite
directions ( 180°), then AB AB. The scalar product is negative
when 90° 180°.
The unit vectors i, j, and k, which were defined in Chapter 3, lie in the positive
x, y, and z directions, respectively, of a right-handed coordinate system. Therefore,
it follows from the definition of that the scalar products of these unit
vectors are
The dot product is simple to evaluate from Equation 7.3 when A is either perpendicularor parallel to B. If A is perpendicular to B ( 90°), then AB 0.(The equality AB = 0 also holds in the more trivial case when either A or B iszero.) If vector A is parallel to vector B and the two point in the same direction( 0), then AB AB. If vector A is parallel to vector B but the two point in oppositedirections ( 180°), then AB AB. The scalar product is negativewhen 90° 180°.The unit vectors i, j, and k, which were defined in Chapter 3, lie in the positivex, y, and z directions, respectively, of a right-handed coordinate system. Therefore,it follows from the definition of that the scalar products of these unitvectors are
การแปล กรุณารอสักครู่..