L=2piR = 282.6 deci R = 282.6 / (2pi) = 141.3 / pi = 45
A cerc = pi R la patrat = pi * 45 la patrat = 2025 pi = 6358,5
folosesti regula de 3 simpla:
A cerc .... 360 grade
A ceruta ... 84 grade
rezulta A ceruta = A cerc * 84 / 360 = 6358,5 * 84 / 360 = 1483,65