Let a and b be two unit vectors and is the angle between them. Then, a + b is a unit vector, if

Step-by-step solution

a + b is a unit vector if | a + b |=1 | a + b |^2=1 ( a + b ) ( a + b )=1 | a |^2+| b |^2+2( a b )=1 1+1+2(a b)=1 2( a b )=-1 a b =- 1 2 | a || b | =- 1 2 1 1 =- 1 2 =- 1 2 Hence, = 2 3