Question

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

Answer 1

A. 3 cm and 3√13 cm B. 3√13 cm and 2√13 cm
C. 5 cm and 13 cm

Answer 2

that is Easy! :o

Answer 3

None of the answers make sense, i plugged them into the equation and it didnt work out...

Answer 4

wht does this mean?

Answer 5

AD/AB=AB/AC

Answer 6

when the length AD is div by AB the result is = to length AB over AC but none of the answers satisfy this.. i think

Answer 7

what the

Answer 8

We can see that AC = AD + DC, so AC = 13. Take the given equation and cross multiply to get AD*AC = AB^2. Then plug in 9 and 13 and we have AB^2 = 117, so AB = Sqrt(117) = Sqrt(9*13) = 3 Sqrt(13).

Now that we know AB, since BDA and BDC are right angles, the Pythagorean Theorem tells us that AD^2 + BD^2 = AB^2, or 9^2 + BD^2 = 117 -> BD = Sqrt(36) = 6. We can then use this to compute BC the same way:
BD^2+DC^2 = BC^2
6^2+4^2 = BC^2
36+16 = 52 = BC^2, so
BC = Sqrt(52) = 2 Sqrt(13).