`text( Triangle Law )`

If two non-zero vectors can be represent by the two sides of a triangle taken in same order, then their resultant is represented by third side of the triangle taken in the opposite order. Consider two vectors `vec A` and `vec B` at an angle `theta` between them.

`text(Finding)` `vec A+ vec B` First draw vector `vec A` `(vec (OP))` in the given direction. Then draw vector; starting from the head of the
vector `vec A`. Then close the triangle.
`vec R(vec (OQ))` will be their resultant

If two non- zero vectors can be represented by the two adjacent sides of a parallelogram, then their resultant is represented by the diagonal of the parallelogram passing though the point of intersection of the vectors. Suppose two vectors `vec A` and `vec B` shown in fig.

When a vector `vec B` is reversed in direction, then the reversed vector is written as `vec B` then

`vec A-vec B=vec A+(-vec B)`

Finding `vec A - vec B` : First draw vector `vec A(vec (OP))` in the given direction. Then draw vector `vec B(vec (PQ))` starting from head of the vector `vec A`. Then close the triangle, `vec R ( vec (OQ))` be their resultant

Finding `vec A -vec B` : Draw vectors `vec A(vec (OP))` and `- vec B(vec (OQ))` starting from a common point `O`. Then complete the parallelogram. The diagonal `vec (OS)` will represent their resultant.