By definition
[tex]\cos (angle)=\frac{\text{ adjacent side}}{\text{ hipotenuse}}[/tex]From the picture
[tex]\begin{gathered} \cos (\theta)=\frac{a}{c} \\ \cos (\theta)=\frac{8.09}{12.4} \\ \cos (\theta)=0.65 \end{gathered}[/tex]By definition
[tex]\sin (angle)=\frac{\text{ opposite side}}{\text{ hipotenuse}}[/tex]From the picture:
[tex]\begin{gathered} \sin (\theta)=\frac{b}{c} \\ \sin (\theta)=\frac{9.4}{12.4} \\ \sin (\theta)=0.76 \end{gathered}[/tex]By definition
[tex]\tan (angle)=\frac{\text{ opposite side}}{\text{ adjacent side}}[/tex]From the picture
[tex]\begin{gathered} \tan (\theta)=\frac{b}{a} \\ \tan (\theta)=\frac{9.4}{8.09} \\ \tan (\theta)=1.16 \end{gathered}[/tex]Isolating θ from the previous equations:
[tex]\begin{gathered} \theta=\arccos (0.65)=49.46\text{ \degree}\approx49\text{ \degree} \\ \theta=\arcsin (0.76)=49.46\text{ \degree}\approx49\text{ \degree} \\ \theta=\arctan (1.16)=49.24\text{ \degree}\approx49\text{ \degree} \end{gathered}[/tex](The difference between the values is caused by rounding errors)
