If are unit vectors, find the angle between


Since,


Let &


Angle between is and angle between is



By vector addition method;


we have:



=2(1+cos θ)



=2(1-cos θ)


So,




Now in the parallelogram:


Area of parallelogram= (product of two sides and the sine of angle between them)


i.e. (1)


Also area of parallelogram= sum of area of all four triangle


And area of each triangle =


So, Area = 2


Since are supplementary


A= 4= (2)


From (1) &(2) we get:





1