# Not right angled triangle! help?!

I will use OB as the dotted line segment between O and B in your diagram. Since $d_1,d_2$ are distances, where those dotted lines meet OB, they form right angles. So, you can use trigonometry for those smaller triangles. $|AB| = d_1\sin \phi$ and $|BC| = d_2\cos \theta$. Then the angle ABC is just $\phi + (90^\circ - \theta)$.