Part D $-$ Find the direction angle a when given direction angles $$ and $y$

As shown, a force of $280$ lb acts at the tip of a tower. Two of the force's direction angles are known, ${}_{R1}=35$ and ${}_{R1}=68\mathrm{.}5,$ that define the angles between the force and the $y$ and $z$ axes, respectively. Find ${}_{R1},$ the angle between the $x$ axis and the force.

Express your answer in degrees to three significant figures.

View Available Hint$($s$)$

${}_{R_1}=$