tolong no 7 besok uts

BC² = AC² + AB²
       = 10² + 10²
       = 100 + 100
       = 200
BC = √200
BC = 10√2

BD = DC = 1/2 x BC = 1/2 x 10√2 = 5√2

AD² = BD x BD
       = 5√2 x 5√2
       = 25 x 2
       = 50
AD = √50
AD = 5√2 cm

Jawaban A