Grid North:
Grid North is the direction of the vertical grid lines shown on a map, pointing towards the top of the map.
Magnetic Variation:
Magnetic variation is the angular difference between True North and Magnetic North. It varies based on location and time.
Cardinal Points:
Cardinal points are the four main directions on a compass: North, East, South, and West.
Magnetic North:
Magnetic North is the direction a magnetic compass needle points, which aligns with the Earth’s magnetic field.
In the adjoining figure, $\triangle CAB$ is a right triangle, right angled at A and $AD \perp BC$. Prove that $\triangle ADB \sim \triangle CDA$. Further, if $BC = 10$ cm and $CD = 2$ cm, find the length of AD. 
In the adjoining figure, TP and TQ are tangents drawn to a circle with centre O. If $\angle OPQ = 15^\circ$ and $\angle PTQ = \theta$, then find the value of $\sin 2\theta$. 