Step 1: Note down the given information. According to that make an imaginary figure.

          NOTE:  Pole height AB= 15 meters

                        Pole shadow length BC = 5 \sqrt{3}

                      Angle of elevation of sun rays  = ?

Step 2: Find the Appropriate trigonometric ratios to calculate angle of elevation.

            From the right triangle.

                     \tan \theta = \frac{opposite}{adjacent}

                     \tan \theta = \frac{AB}{BC} = \frac{15}{5 \sqrt{3}}

                   \tan \theta = \frac{3}{ \sqrt{3}} = \frac{(\sqrt{3})^2}{\sqrt{3}}                  

                   \tan \theta = \sqrt{3}

Step 3:  Search for the equivalent trigonometric ratio angle values.

                EXAMPLE: \tan \theta = \sqrt{3}

                                   \tan \theta = \tan 60\degree (Since, \tan 60\degree = \sqrt{3})

                                     \theta = 60 \degree

                      Therefore the angle of elevation  = 60\degree