Find the coordinates of a point A, where AB is the diameter of a circle whose centre is (2, – 3) and B is (1, 4).
Let the coordinates of point A be (x, y).
Mid-point of AB is (2, −3), which is the center of the circle.
\(\therefore\,(2,-3)=(\frac{x+1}{2},\frac{y+4}{2})\)
\(\Rightarrow \, \frac{x+1}{2}=2\, and\,\frac{y+4}{2}=-3\)
\(\Rightarrow \,x+1=4\,and\,y+4=-6\)
\(\Rightarrow \,x=3\,and\,y=-10\)
Therefore, the coordinates of A are (3,-10)
What is the angle between the hour and minute hands at 4:30?
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 $\sin 2\theta$. 
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. 