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# If side BE has length 10 and side AC has length

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Manager
Joined: 13 Apr 2010
Posts: 90
If side BE has length 10 and side AC has length  [#permalink]

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22 Oct 2017, 04:16
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Difficulty:

45% (medium)

Question Stats:

78% (01:44) correct 22% (02:13) wrong based on 32 sessions

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If side BE has length 10 and side AC has length 8, what is the area of the triangle BOC ?

A. $$2\sqrt{3}$$
B. $$4\sqrt{3}$$
C. $$6\sqrt{3}$$
D. $$8\sqrt{3}$$
E. $$12\sqrt{3}$$

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Math Expert
Joined: 02 Aug 2009
Posts: 6549
If side BE has length 10 and side AC has length  [#permalink]

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22 Oct 2017, 08:36
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1
sb0541 wrote:
If side BE has length 10 and side AC has length 8, what is the area of the triangle BOC ?

A. $$2\sqrt{3}$$
B. $$4\sqrt{3}$$
C. $$6\sqrt{3}$$
D. $$8\sqrt{3}$$
E. $$12\sqrt{3}$$

A very SIMPLE solution..

Triangle BOC is 30-60-90 angle with right angle at O...
HOW?

Angle DEB=60=AngleABE ( Alternate angles)..
so check triangle DBO
angle ABO = 60.... angle BAO = 30 so ANGLE BOA = 180-60-30=90...
so BE and AC intersect at 90..

therefore Triangle OBC is 90 at O...
Now check triangle ABC ( 30-60-90), sides are in ratio $$1:\sqrt{3}:2$$
hyp = ratio of 2 in $$1:\sqrt{3}:2$$ so BC = $$\frac{8}{2}=4$$

Now OBC is also 30-60-90 where hypotenuse is 4, so other two sides = $$\frac{4}{2}$$ and $$\frac{4}{2}*\sqrt{3}$$..
so $$AREA = \frac{1}{2}*\frac{4}{2}*\frac{4}{2}*\sqrt{3} = 2*\sqrt{3}$$

A
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3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html

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If side BE has length 10 and side AC has length &nbs [#permalink] 22 Oct 2017, 08:36
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