Flag of Algeria — construction sheet
Own work. Geometry and dimensions from Algerian Flag Law.

The length of the rectangle is equal to one and half its width (height of the flag). This rectangle is divided according to the small median in two halves. The green colour half is placed inside, against the shaft.
The white colour half is placed outside. The star is composed of five branches. It is written down in a circle whose radius is equal to the eighth of the height of the flag.
It detaches itself entirely on the white bottom of the flag; two tips are on the small median of the rectangle and a tip on the big median.
The radius of the outside circle of the crescent is equal to the quarter of the height of the flag.
The radius of the interior circle of the crescent is equal to the fifth of the height of the flag. The two tips of the crescent delimit a big equal bow to the five sixth of the circumference of the outside circle.

The centre of the outside circle of the crescent is in the centre of the rectangle.— English translation of Algerian Flag Law from Embassy of People's Democratic Republic of Algeria in Pretoria
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This construction sheet includes two irrational dimensions that have been derived (calculated) from the given dimensions:

A: Distance from the vertical centerline of the flag to the vertical centerline of the small arc on the crescent.
B: Distance from the vertical centerline of the flag to the vertical centerline of the star.
Simple mathematics reveals that the distance between the two points on the crescent is precisely equal to the diameter of the imaginary circle around the star.  This leads to some redundancy in the drawing.
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