ABC drept in A => conform teoremei lui pitagora ca BC la a doua=AC la a doua + AB la a doua
BC la a doua=9 la a doua + 12 la a doua
BC la a doua=81+144=225
BC=15
ABC drept in A => conform teoremei inaltimii AD= AC x AB supra BC
AD _|_ BC 9x12 supra 15=7,8