Given that bd is both the median and altitude of triangle abc, congruence postulate sas is used to prove that triangle abc is what type of triangle?

Isosceles

Step-by-step explanation:

Consider triangle ABC, BD is the median and the altitude drawn to the side AC. This segment (BD) divide the triangle ABC into two triangles: ABD and CBD.

In these triangles:

Thus, by SAS postulate, triangles ABD and CBD are conruent. Congruent triangles have congruent corresponding sides. Hence, AB=CB.

If in triangle ABC, AB=BC, then this triangle is isosceles.