Question

If u is a unit vector, find u · v and u · w. (assume v and w are also unit vectors.) equilateral triangle

Answer 1

solution:

we know that ,

u.v = ΙuΙ ΙvΙcosθ

here,

θ =60° (since the given triangle is equilateral triangle)

u.v = ΙuΙ ΙvΙcos60°

     = 1 x 1 x 1/2

u.v = 1/2

now, u.w = ΙuΙ ΙwΙcosθ

              = ΙuΙ x cos(60x2)

u.w = -1/2