Phileas Fogg, the protagonist of "Around the World in Eighty Days," is a methodical, disciplined, and determined individual. He is a man of few words, relying on actions and calculations. His decision to travel around the world in eighty days, driven by a wager, shows his adventurous spirit and his belief in logic and precision. Fogg’s journey, full of challenges and unpredictable events, reveals his resilience, intelligence, and calm demeanor in the face of adversity. He is a character that exemplifies the values of perseverance and adventure.
Explain the construction of a spherical wavefront by using Huygens' principle.
The slope of the tangent to the curve \( x = \sin\theta \) and \( y = \cos 2\theta \) at \( \theta = \frac{\pi}{6} \) is ___________.