1perfect .. now just waiting for someone to calculate .. vectorially ... just proceeding eureka's method .. or something else ..
26 Answers
62One more thing...
Why do you have to make things more complicated by taking root 2 in the calcualtion?
it was better the way sky did first.. take (6,6,0) etc
and then divide by root 2 if you are finding lengths. or divide by 2 if you are finding areas :)
good luck :)
24@ sky..........i didnt said about ur typing mistake......
i was replying to post #15 of deepanshul about my soln...........[1][1]
1
1no no dont apologise//
and yes eureka.. it WAS NOT a typo...
yeh bhi galati hi tha...
main nahi dekhi thi...
too stupid a work for a <one-month jee-aspirant ......
am sorry...
1oho bhaiya .. got it .. sorry sky .. i apologise .. ur method is the best ....
62deepanshu and Ankit.. skky is correct this time
see carefully
each side length is 6 root 2
Only thing she has to do is divide the final answer by root 2 :)
1bhaiya sky ka post check toh kijiye .. she is still incorrect ..
1sorry....
mera yeh galti karne kii adat ni jaegi ... [2]
the points are A(0,0,0) , B(6,0,6), C(0,6,6) and D(6,6,0).
i think this way calculation is simple...
24taking A as origin
B=b,C=c,D=d
=>E=c/3 and F=b+2c/3
now write EF and FD and take cross product
62yes ankit.. perfect :)
That is why i was saying to look at the 3 triangles seperately :)
1Nishant bahiya .. a simple approach(but bulky process) just struck me
EF2 = EC2 + CF2 - 2EC.CF cos60°
so we get the value of EF
Similarly we can find ED and DF
Then we can use Heron's formula to calculate the area ...
1well we can take points...
A(0,0,0) , B(0,6,0), C(0,0,6) and D(6,0,0).
now the point E is 0,0,2
and point F is 0,2,4 .
now find area..........
1DF2 +FC2=DC2
DF2=36-9=27 ( FC= 3 units)
DF=√27
dont know what to do further
trying to think
1
regular tetrahedron with each side = 6 units
AE : EC = CF : FB = 1:2
find the area of triangle DEF ....