Write how we can build up a civilized society with the help of the extract.
A civilized society can be built on tolerance rather than love. Love is unrealistic for governing public affairs, but tolerance allows people to coexist peacefully despite differences. This approach ensures stability, cooperation, and long-term unity among different communities.
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 ___________.