a_1=sin60^0=\frac{\sqrt3}{2}
a_2=sin45^0=\frac{\sqrt2}{2}
a_3=x
W ciągu geometrycznym stosujemy wzór
a_2^2=a_1*a_3
(\frac{\sqrt2}{2})^2=\frac{\sqrt3}{2}*a_3
\frac{2}{4}=\frac{\sqrt3}{2}*a_3
\frac{\sqrt3}{2}*a_3=\frac{1}{2}/:(\frac{\sqrt3}{2})
a_3=\frac{1*2}{2*\sqrt3}
a_3=\frac{1}{\sqrt3}=\frac{\sqrt3}{3}=tg30^0
Odp. C)