prove it thx! (Worried)

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- Oct 15th 2013, 10:09 PMparmisgeometry prove
prove it thx! (Worried)

- Oct 16th 2013, 03:32 AMemakarovRe: geometry prove
If it said AE/AF = CD/BD, then both cross-products would equal the area of the parallelogram.

- Oct 16th 2013, 04:27 AMMINOANMANRe: geometry prove
Emakarov is right this ratio is not valid : it is valid only if ABCD is a rombus.

- Oct 16th 2013, 07:07 AMparmisRe: geometry prove
- Oct 16th 2013, 07:23 AMemakarovRe: geometry prove
As I said in post #2, AE * BD = AF * CD = area of the rhombus.

- Oct 16th 2013, 07:45 AMparmisRe: geometry prove
Attachment 29489

answer these too. thx

in 1, question is: What fraction of the ABCD rhombus's area is the MNP Triangle's area? - Oct 16th 2013, 08:03 AMemakarovRe: geometry prove
Hint: area of △MNP = area of △MPB because MP is the median. And area of △MNB = 1/2 area of MBCN.

- Oct 16th 2013, 08:10 AMparmisRe: geometry prove
I undrestand area of △MNP= area of △MPB but why area of △MNB = 1/2 area of MBCN?

why area of △BNC = 1/2 area of MBCN? http://www.qalamro.ir/smaeel/2/(24).gif - Oct 16th 2013, 08:23 AMemakarovRe: geometry prove
- Oct 16th 2013, 08:35 AMparmisRe: geometry prove
Thank you very much.

someone prove rhombus's area formula that i wrote up in picture in 6#.http://www.qalamro.ir/smaeel/2/(7).gif - Oct 16th 2013, 08:42 AMemakarovRe: geometry prove
Generally, you should start a new thread for each new question. People are far less likely to read through several posts to discover that there is an unanswered question in the end.