vmathhelp
Can someone help me with Geo Problem!
Diagonal AC divides a trapezoid ABCD two similar triangles ABC and ACD. Find AC if BC=4cm and AD=9cm
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vmathhelp
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@ganeshie8 I need help
vmathhelp
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@ghazi @lalaly @AccessDenied
kajolc.2496
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Are these triangles similar by area?
kajolc.2496
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Is not there any fig. for this?
campbell_st
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I think it looks like this|dw:1356206771435:dw|
the angles marked x are equal by alternate angles in parallel lines
ghazi
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|dw:1356207039082:dw|
vmathhelp
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Now what do i do?
ghazi
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have you provided whole information?
vmathhelp
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yes
kajolc.2496
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I think there is something we r missing..
campbell_st
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well the corresponding sides in the triangles are
triangle ABC and triangle ACD are
AB AC
AB DC
BC AD
now you need to use the ratio's of corresponding sides in similar triangles
kajolc.2496
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but ques. does'nt say that it divides the triangles in equal areas!
kajolc.2496
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that's wat i was confirming earlier
vmathhelp
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AD:BC = 2.25
kajolc.2496
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SIMILARITY CAN ONLY BE USED WHEN AREAS ARE EQUAL
campbell_st
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oops corresponding side should be AC and DC
so using the ratio of corresponding sides
\[\frac{4}{9} = \frac{AB}{AC}= \frac{AC}{ DC}\]
vmathhelp
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what happens next?
vmathhelp
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@campbell_st
campbell_st
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who knows.... it doesn't make sense to me... there seems to be something missing from the question.
campbell_st
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Oh, and triangles can be similar and have different areas the ratio will be the linear ratio squared.
so the ratio of areas in the triangles is ABC:ACD = (4/9)^2
vmathhelp
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@ghazi is there missing info?
ghazi
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i am confused
vmathhelp
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wat r u confused about?
ghazi
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there is something missing in it