Cos 72 degrees
| Input |
|---|
| cos(72 °) |
| Exact result |
| 1/4 (sqrt(5) – 1) |
| Decimal approximation |
| 0.309016994374947424102293417182819058860154589902881431067… |
| Reference triangle for angle 72° |
|
width | cos(72 °) = 1/4 (sqrt(5) – 1)~~0.309017 height | sin(72 °) = sqrt(5/8 + sqrt(5)/8)~~0.951057 |
| Minimal polynomial |
| 4 x^2 + 2 x – 1 |
| Continued fraction |
| [0; 3, 4^_] |