Question 488188
{{{drawing(300,300,0,10,0,10,


triangle(2,5,8,5,4,8),
triangle(2,5,8,5,4,2),
locate(2,5,A),
locate(8,5,D),
locate(4,8,B),
locate(4,2,C),
line(4,8,4,2)
)
}}}

If we assume that the labeling in the problem ("Given triangle BAD is congruent to triangle CAD") is correct, then right away we can claim BA = CA and triangle ABC is isosceles (you might want to say BA = CA --> ABC is isosceles in your proof).


If the labeling is incorrect (e.g. triangle BAD is actually congruent to triangle CDA") then that is a mistake on the textbook. Just make sure you also label your points correctly, matching corresponding ones next to each other.


Either way, you would want to specify that BA = CA implies that triangle ABC is isosceles.