2009 · Q34
ABC is a triangle and the perpendicular drawn from A meets BC in D. If AD 2 = BD.DC, then which one of the following is correct?
Elementary MathematicsGeometry
- AABC must be an obtuse angled triangle
- BABC must be an acute angled triangle
- CEither ∠B ≥ 45° or ∠C ≥ 45°
- DAC 2 = AB 2 + BC 2
Explanation
AD² = BD·DC with AD ⊥ BC makes ∠A = 90°; so B or C ≥ 45°.