Which of the following equations could be solved to determine the length of QR?

The vector written in its generic form is given by:
 v = lvl cos theta ° i + lvl without theta ° j
 Where.
 lvl: magnitude of the vector
 theta: angle of the vector with respect to the x axis.
 For this case we have the following vector:
 v = 3 cos 123 ° i + 3 without 123 ° j
 Where,
 lvl = 3
 theta = 123 °
 
 The magnitude and direction angle for the vector v is:
 D. 3, 123 °