Theory:

We are aware of the four directions, namely North, South, East and West.
 
15.svg
 
The four directions altogether form \(360^\circ\).
 
From the figure, we can come to the following inferences.
 
1. North and South are opposite each other. Therefore, they are straight angles to each other.
 
2. East and West are opposite each other. Therefore, they are straight angles to each other.
 
3. East is one-quarter away in the clockwise direction to North.
 
The total angle of the directions \(= 360^\circ\)
 
One quarter can also be written as \(\frac{1}{4}\).
 
Therefore, \(\text{one-quarter of the total angle}\) \(= \frac{\text{Total angle of the directions}}{4}\)
 
\(= \frac{360}{4}\)
 
\(= 90^\circ\)
 
Thus, it is understood that North and East are at right angles in the clockwise direction.
 
Let us look at the tabular column given below for a better understanding.
 
Directions at right angles in the clockwise directionDirections at right angles in the anti-clockwise direction
North and EastNorth and West
East and SouthWest and South
South and WestSouth and East
West and NorthEast and North
 
Important!
Like how right angles are one-quarter of an angle, straight angles are also one-half of the angle.
 
\(\text{One-half of the angle}\) \(= \frac{\text{Total angle}}{2}\)
 
\(= \frac{360}{2}\)
 
\(= 180^\circ\)
 
Straight angles can also be written as 'Sum of two consecutive right angles'.