Question

AD/AB=AB/AC. If AD=9 cm and DC=4 cm, then AB= ___ and BC= ___.

Answer 1

AD/AB=AB/AC by cross multiplying you get

AD*AC = AB*AB

so AB^2 = AD*AC

AC=AD+DC =9+4 = 13
AB^2 = AD*AC = 9(13) = 117

so AB = sqrt(117)

Answer 2

to find BC use
ABC is right triangle so
AB^2 + BC^2 = AC^2
117 + BC^2 = 13^2

BC^2 = 169-117 = 52

BC= sqrt(52)

Answer 3

to simplify...

sqrt(117) = sqrt(9*13) = 3sqrt(13)
sqrt(52) = sqrt(4*13) = 2sqrt(13)

Answer 4

Thank you so much

Answer 5

its my pleasure XD

Answer 6

:D