Hachures: - Hachures are short lines drawn to represent slope direction. - They are drawn perpendicular to contour lines and indicate steepness with thicker and closely spaced lines.
Hill Shading: - Hill shading uses light and shadow effects to give a three-dimensional appearance to hills. - It visually represents the shape of landforms by adding shades on one side and light on the other.
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 $\sin 2\theta$. 