From Mechanics

In part a) the resultant \displaystyle \mathbf{R} is seen to be

\displaystyle \begin{align} & \mathbf{R} =11\textrm{.}1\mathbf{i}+3\textrm{.}93\mathbf{j} \ \text{N}\\ \end{align}

Also according to the theory

\displaystyle \tan \alpha =\frac{V}{H} where \displaystyle H is the horizontal component of the resultant and

\displaystyle V is the vertical component of the resultant.

Thus

\displaystyle \tan \alpha =\frac{\text{3}\textrm{.}\text{93}}{\text{11}\textrm{.}\text{1}}=0\textrm{.}354

giving

\displaystyle \alpha =19\textrm{.}5{}^\circ