Show that ABC is a straight line in each of the following diagrams, given angles around point B.

The angles are $\angle DBA = 49^\circ$, $\angle DBE = 90^\circ$ (indicated by the square symbol), and $\angle EBC = 41^\circ$.

$$
\angle DBA + \angle DBE + \angle EBC = 49^\circ + 90^\circ + 41^\circ = 180^\circ
$$

Since