Answer: Choice A) sqrt(136)
This is equivalent to 2*sqrt(34)
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Explanation:
First let's find BD
The three triangles are similar, allowing for the proportion to be set up
AD/BD = BD/DC
9/x = x/8
9*8 = x*x
x^2 = 72
x = sqrt(72)
BD = sqrt(72)
Now we can use the pythagorean theorem. Focus on triangle BDC.
The legs are BD = sqrt(72) and DC = 8. Let's find the hypotenuse
(BD)^2 + (DC)^2 = (BC)^2
(sqrt(72))^2 + (8)^2 = m^2
72 + 64 = m^2
136 = m^2
m^2 = 136
m = sqrt(136)
We can simplify this but your teacher has chosen not to. If you want to simplify, then,
m = sqrt(136)
m = sqrt(4*34)
m = sqrt(4)*sqrt(34)
m = 2*sqrt(34)
