# The resultant of two vectors P and Q is R.If Q is doubled then the new resultant vector is perpendicular to P.Then R is equal to?

##### 1 Answer

Sep 21, 2017

Let the angle between two vectors

So we can write

When Q is doubled then let the resultant vector be

Again by the given condition

So

Combining [2] and [3] we get

combining [1] and [4] we get