In triangle ABC, the median BD is half of the side AC. Find Angle B

Since BD is equal to half the length of AC and BD is the median of the triangle, then AD = DC = DB. Hence triangles ADB and BDC are isosceles. The angles of the triangles on the AC side add up to 180 °. Let one of their angles be equal to X, then the other is equal to 180-X. Thus, we will designate other angles of isosceles triangles. As a result, the angle B will be equal to the expression (180 – X) / 2 + X / 2, which is equal to 90 °.