If the vectors E1 and E2 are two unit vectors with an angle of 60 ° in the plane, a = 2E1 + E2, B = - 3E1 + 2e2, then the angle between a and B is?

If the vectors E1 and E2 are two unit vectors with an angle of 60 ° in the plane, a = 2E1 + E2, B = - 3E1 + 2e2, then the angle between a and B is?

As a result, we will be able to be 1 × 1 × cos (60) at the end of (1 / 2) and we will be able to (2E1 + 2e2) (- 3E1 + 2e2) (- 3E1 + 2e2) = -6e1 and#; (and 4e-1e2-3e1e1e2-3e1e1e2 + 2e2; and we will be able to (2E1 + 2E1 + 2e2) (- 3E1 + 2e2) = - 6e1-6e1 and\\\\\\35;? (178; and we will be able to be able to be able to be able to be able to be a \\\\\\\\\\\\\\\; = - 1 / 2;? = 120 °; hello