Flower Petal Study #2 - Petals Created With Arcs 

Each petal is formed by two identical arcs joined by an inner turn. The formula for the
final turn = 360/number of petals−( 2 × arc angle) + inner turn

This formula accounts for: The total angle the turtle turns while drawing each arc, the sharp turn between the arcs and the final adjustment needed to evenly space each petal around a circle. If this result is less than 360°, 360° is added to ensure the turtle maintains the correct heading for the next petal.