ABC is a triangle and the perpendicular drawn from A meets BC in D. If AD2 = BD ⋅ DC, then which one of the following is correct?
1
ABC must be an obtuse angled triangle
2
ABC must be an acute angled triangle
3
Either ∠B ≥ 45° or ∠C ≥ 45°
4
BC2 = AB2 + AC2