Direction angle of a vector  Vectors
Direction angle of a vector
It should be clear by now that a quantity will not be considered a vector quantity if the magnitude or the direction is missing. In this section, we will shift our focus to learn how to indicate the direction of a vector.
Basic concepts:
 Use sine ratio to calculate angles and sides (Sin = $\frac{o}{h}$ )
 Use cosine ratio to calculate angles and sides (Cos = $\frac{a}{h}$ )
 Use tangent ratio to calculate angles and sides (Tan = $\frac{o}{a}$ )
Related concepts:
 Angle and absolute value of complex numbers
Lessons

1.
Determine the direction angle of the following vectors: