Concept: Letter styles refer to the formatting and alignment used in business or formal letters. The main difference between letter styles lies in how paragraphs, addresses, and complementary closes are aligned.
Difference Between Letter Styles: \[ \begin{array}{|c|c|c|c|} \hline {Feature} & {Indented Style} & {Fully Blocked Style} & {Semi-Blocked Style} \\ \hline \text{Alignment} & \text{Paragraphs indented} & \text{All text left aligned} & \text{Mix of block and indented} \\ \hline \text{Paragraph Format} & \text{First line indented} & \text{No indentation} & \text{Paragraphs may be indented} \\ \hline \text{Address Placement} & \text{Slight indentation} & \text{All parts start from left margin} & \text{Some parts shifted right} \\ \hline \text{Closing} & \text{Indented to the right} & \text{Starts from left margin} & \text{Often aligned right} \\ \hline \text{Appearance} & \text{Traditional and formal} & \text{Modern and simple} & \text{Balanced and semi-formal} \\ \hline \end{array} \]
Explanation:
Conclusion: Indented style is traditional, fully blocked style is modern and widely used in business, and semi-blocked style combines features of both for a balanced appearance.
A racing track is built around an elliptical ground whose equation is given by \[ 9x^2 + 16y^2 = 144 \] The width of the track is \(3\) m as shown. Based on the given information answer the following: 
(i) Express \(y\) as a function of \(x\) from the given equation of ellipse.
(ii) Integrate the function obtained in (i) with respect to \(x\).
(iii)(a) Find the area of the region enclosed within the elliptical ground excluding the track using integration.
OR
(iii)(b) Write the coordinates of the points \(P\) and \(Q\) where the outer edge of the track cuts \(x\)-axis and \(y\)-axis in first quadrant and find the area of triangle formed by points \(P,O,Q\).