Find a ·
b. |a| = 60, |b| = 30, the angle between a and b is 3π/4.

The dot product is used to determine the magnitude of the resultant vector of two component vectors. It is expressed as a·b. It does not literally mean that you multiply their values. Instead, you multiply their matrices. However, since we cannot find matrices, let's just find the resultant vector through theorems involving triangles. By cosine law:

R = √[a² + b² - 2abcos(3π/4)]
R = √[60² + 30² - 2*60*30*cos(3π/4)]
R = 83.94

Thus, a·b = 83.94

Ithink it can be put them in order by 4 possible ways.that mean 3 group of 10 rocks,or an another group of 8 rocks.