Posted by **yuni** on Saturday, December 24, 2011 at 9:51pm.

the position vectors of the point A,B & C respect to O are a=3i-2j+4k, b=i+3j-4k, c=-2i+5j-3k. Find

a)the angle between a+b and a-b

b)lamdar if vector a is perpendicular to b+lamdar k.

- math -
**drwls**, Sunday, December 25, 2011 at 6:26am
How do you define "lambdar" ?

As for part (a), compute these two vectors:

a + b = 4i +j +0k

a - b = 2i -5j +4k

Their magnitudes are:

|a+b| = sqrt(16 + 1) = sqrt17

|a-b| = sqrt(4 +25 + 16) = sqrt45

(a+b)*(a-b) = 8 -5 = 3

= (sqrt17) x (sqrt45) cos theta

cos theta = 3/sqrt765 = 0.108

theta = 83.8 degrees

In the above, * denotes a dot product and x denotes normal scalar multiplication

## Answer this Question

## Related Questions

- Please Help asap for math - Given the following: vector u= [-2,-1,2] and vector ...
- Math: Vectors - Find any vector w that is perpendicular to both vector "u = 3j...
- Math - The position vectors A and B with respect to the origin O,(-8,5) are (12...
- math - The position vectors of points A and B with respect to the origin 0, are...
- math - The position vectors of points A and B with respect to the origin 0, are...
- Maths Vector Helpppp - The points A and B have position vectors, relative to the...
- math - Find the unit vector perpendicular to the plane ABC where the position ...
- math - Point T is the midpoint of a straight line AB. Given the position vectors...
- Calculus - SORRY, i wrote this question wrong before ... u, v, w are UNIT ...
- science (physics) Need to solve this today please - (a) Express the vectors A, B...