Find a unit vector that has the same direction as the vector a and the opposite direction of the vector a. a = −15i + 8j

The unit vector is given by the following formula:
 a '= (a) / (lal)
 Where,
 a: vector a
 lal: Vector module a
 We are looking for the module:
 lal = root ((- 15) ^ 2 + (8) ^ 2)
 lal = 17
 Same direction:
 a = -15i + 8j
 The unit vector is:
 a '= (1/17) * (- 15i + 8j)
 Opposite direction:
 a = 15i - 8j
 The unit vector is:
 a '= (1/17) * (15i - 8j)
 
 a unit vector that has the same direction as the vector a is:
 a '= (1/17) * (- 15i + 8j)
 a unit vector that has the opposite direction of the vector a is:
 a '= (1/17) * (15i - 8j)