Trigonometry in Learning to Fly Part 4

[FreePlacki]

When you explain the process of drawing the triangles, you convert the angle to radians:

2 * PI = 360°
     x = 60°

360° * x = 2 * PI * 60°    | divide by 2
180° * x = PI * 60°        | divide by 180°
       x = PI * 60° / 180° | simplify
       x = PI * 2 / 3      | shuffle constant to left
       x = 2 / 3 * PI      | enjoy

But x = 60° = 1 / 3 * PI.
The values you obtained: 2/3 PI and 4/3 PI are correct, but that's not because we rotate by 60° and 120° but instead by 120° and 240°.

---

Also one small mistake: on the drawing of the unit circle, labels on the axis are swapped (if you say that x=cos(α) and y=sin(α)).

[Patryk Wychowaniec]

Hi, thanks for reporting! I'll take a look over the weekend and update the article 🙂