Answer:

Step-by-step explanation:
To find the distance between (8, -3, 4) and (6, -4, 1), use the distance formula for (x,y,z) points. It is very similar to (x,y) points.

Answer:

Step-by-step explanation:
we know that
The formula of law of cosines is equal to

where
a, b and c are sides. C is the angle opposite side c
In this problem we have

substitute the given values





