Answer:
Givens
[tex]m\angle ABD=43\°\\m\angle DBC=47\°[/tex]
To probe [tex]\triangle ABC[/tex] is a right triangle, we have to demonstrate that the vertex B holds a right angle, that is [tex]m\angle ABC = 90\°[/tex]
Now, by sum of angles, we know
[tex]m\angle ABC = m\angle ABD + m\angle DBC[/tex]
By given we know that
[tex]m\angle ABD=43\°\\m\angle DBC=47\°[/tex]
Replacing these values, we have
[tex]m\angle ABC = 43\°+ 47\°=90\°[/tex]
Then, [tex]\angle ABC[/tex] is a right angle by definition.
Finally, [tex]\triangle ABC[/tex] is a right triangle by definition, with right angle at vertex B.