S.178 T.470


a)
\alpha=90-66{,}5=23{,}5°
\sin23{,}5=\frac{x}{6371}
x=2540{,}430...\approx2540\left(km\right)
y=\sqrt[]{2540^2+2540^2}=3592{,}1024...\approx3590\left(km\right)
b)
2\pi\cdot2540\cdot\frac{90}{360}=3989{,}822...\approx3990\left(km\right)