HP (Hewlett-Packard) 50g ユーザーズマニュアル

ページ / 887
Page 9-16
Suppose that you want to find the angle between vectors A = 3i-5j+6kB = 
2i+j-3k, you could try the following operation (angular measure set to degrees) 
in ALG mode: 
1 -  Enter vectors [3,-5,6], press  
`, [2,1,-3], press `.
2 -  DOT(ANS(1),ANS(2)) calculates the dot product 
3 -  ABS(ANS(3))*ABS((ANS(2)) calculates product of magnitudes
4 -  ANS(2)/ANS(1) calculates cos(
θ)
5 -  ACOS(ANS(1)), followed by ,
NUM(ANS(1)), calculates θ
The steps are shown in the following screens (ALG mode, of course):
     
!!!
Thus, the result is 
θ = 122.891
o
.    In RPN mode use the following:
[3,-5,6] ` [2,1,-3] ` DOT
[3,-5,6] ` BS [2,1,-3] ` BS *
/     COS   NUM
Moment of a force
The moment exerted by a force F about a point O is defined as the cross-
product M = r
×F, where r, also known as the arm of the force, is the position 
vector based at O and pointing towards the point of application of the force.  
Suppose that a force F = (2i+5j-6k) N has an arm r = (3i-5j+4k)m. To 
determine the moment exerted by the force with that arm, we use function 
CROSS as shown next: