U konveksnom četverokutu
![ABCD](/media/m/9/c/e/9ce25711ba18d9663b73c3580de4bf5a.png)
vrijedi
![\sphericalangle BAD = 50^\circ](/media/m/d/1/d/d1d5c6a91064659468dad1e97998363c.png)
,
![\sphericalangle ADB = 80^\circ](/media/m/1/a/0/1a094d3d53258aef2d0bab26793dcec7.png)
i
![\sphericalangle ACB = 40^\circ](/media/m/9/c/3/9c3a25bcf0dd3554c06ac8f26d0c5d92.png)
. Ako je
![\sphericalangle DBC = 30^\circ + \sphericalangle BDC](/media/m/1/4/9/149106a0acf954d5155a01d56d864e2d.png)
, izračunaj
![\sphericalangle BDC](/media/m/a/1/b/a1b03191b5c1530f9e9df6179604f8dd.png)
.
%V0
U konveksnom četverokutu $ABCD$ vrijedi $\sphericalangle BAD = 50^\circ$, $\sphericalangle ADB = 80^\circ$ i $\sphericalangle ACB = 40^\circ$. Ako je $\sphericalangle DBC = 30^\circ + \sphericalangle BDC$, izračunaj $\sphericalangle BDC$.