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29 Jun 2022, 16:45
Kudos
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B
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
35%
(medium)
Question Stats:
63% (01:17) correct
37%
(01:14)
wrong
based on 30
sessions
History
Date
Time
Result
Not Attempted Yet
What is CD in the figure above?
A. √2
B. 2
C. √6
D. 2√2
E. 4
Attachment:
1.png [ 3.87 KiB | Viewed 1524 times ]
29 Jun 2022, 18:29
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Bunuel
Two ways.
First, the way I would do it: I'd look at the thing and estimate. AB is 1.7. Is CD longer or shorter? Longer. A is out. How much longer? Not much. Oh, come on, it's just barely longer. C is 2.4 and D and E are both even longer than that. CD is NOT 0.7 longer than AB. There's only one answer choice that's close.
Answer choice B.
I will never understand why, but that answer is not going to satisfy some of you, so here's the "real" math. 1 + BD^2 = 3. BD = \(\sqrt{2}\). BD = BC, so those are two legs of a 45-45-90. The hypotenuse is \(\sqrt{2}\sqrt{2} = 2\).
Answer choice B.
I can't wait to see how many people miss this one because they fall right into the trap of making BD = 2...
29 Jun 2022, 19:59
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Notable triangles
45,45,90
x,x,x\sqrt{ 2 }
45,45,90
x,x,x\sqrt{ 2 }
Attachments
7B0326DA-3A24-4402-B81B-FCB5003B1784.jpeg [ 166.29 KiB | Viewed 875 times ]
