ΔABC; AD-h
AD=12
BC=25
AD²=BD* DC
12²=BD * (BC-BD)
144=BD * (25-BD)
144=25BD-BD²
144-25BD+BD²=0
a=1
b=-25
c=144
Δ=b² -4ac= (-25)² -4* 144
Δ= 625-576
Δ=49
x₁ ; x₂= ( -b + ∧ - √Δ) / 2a
x₁; x₂= (-(-25)+ ∧ - √49 )/2*1
x₁= (25+ 7)/2= 32/2=16
x₂= (25-7)/2= 18/2=9
(x-16)(x-9)=0
x-16=0 ∧ x-9=0
x=16 x=9
BD < DC ⇒ BD=9 ∧ DC=16