Góc 72o72^{o}72o có số đo theo radian bằng
2π5\dfrac{2\pi}{5}52π.
3π5\dfrac{3\pi}{5}53π.
5π3\dfrac{5\pi}{3}35π.
5π2\dfrac{5\pi}{2}25π.
Ta có 72o=72.π180=2π572^{o} = 72.\dfrac{\pi}{180} = \dfrac{2\pi}{5}72o=72.180π=52π.
