Find the lengths of diagonals of the parallelogram constructed on the vectors
p=2a+b and q=a-2b, where a and b are unit vectors and forming an angle of 60°.
62the resultant will be p+q
= 3a-b
|3a-b|2= (3a-b).(3a-b) = 9a2+b2-6a.b
length2 is 9+1-1/2=10-3=7
length = √7
6there are two values of the diagonals!!!!!!!!
i got one as √7 but the other that i was getting was √5 and this was a single choice correct and the two values that i got were present there but paired up with other values!!!!!!
so what will be the other value?