Two vectors have magnitudes 3 unit and 4 unit respectively. What should be the angel between them if the magnitude of the resultant is 7 unit.

Explanation

According to polygon law of vector additin, the resultant of these six vectors is zero. Here `a=b=c=d=e=f`( magnitude)
So`R_x= cos 0+A cos pi/3=A cos (2pi)/3+ Acos (3pi)/3+A cos (4pi)/3+A cos pi/3 =0` As resultant is zero
x component of reesultant `R_x=0], rarr cos 0+cos pi/3+cos (2pi)/3+cos(3pi)/3+cos (4pi)/3+ cos (5pi)/3=0`
[Note: Similarly it can be proved that `sin 0+ sin pi/3+sin (2pi)/3+sin(3pi)/3+sin(4pi)/3
+sin (5pi)/3=0`