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songoku
Jan13-12, 09:00 PM
1. The problem statement, all variables and given/known data
Regular pyramid T.ABCD has square base with side 1 cm. N is the mid-point of AB. Find the length of TN


2. Relevant equations
not sure


3. The attempt at a solution
No information given about the height of the pyramid and the length of the slant-edge, such as TA, so how can we find TN :confused:
Mentallic
Jan13-12, 10:01 PM
Without being given the height of the pyramid (or something equivalent, such as the slant height) then you can't place a value on the length of TN. The only way I can see going about this is to leave the answer in terms of an unknown constant, such as AT, or maybe regular pyramid means something more than just the apex of the pyramid is normal to the centre of the base.
songoku
Jan13-12, 11:29 PM
Without being given the height of the pyramid (or something equivalent, such as the slant height) then you can't place a value on the length of TN. The only way I can see going about this is to leave the answer in terms of an unknown constant, such as AT, or maybe regular pyramid means something more than just the apex of the pyramid is normal to the centre of the base.

Not sure, but I think regular pyramid means that the apex of the pyramid is normal to the centre of the base and the base has equal side, i.e the base is square.

If I remember correctly, the answer is 1/2 √3. But I can't find it. I have provided the complete question
Mentallic
Jan14-12, 12:04 AM
Not sure, but I think regular pyramid means that the apex of the pyramid is normal to the centre of the base and the base has equal side, i.e the base is square.

If I remember correctly, the answer is 1/2 √3. But I can't find it. I have provided the complete question

Ahh ok then, with the answer of \frac{\sqrt{3}}{2} that means the edges connecting to the apex are a length of 1 each, which I guess is what was also implied by the "regular" pyramid.
songoku
Jan14-12, 03:51 AM
Ahh ok then, with the answer of \frac{\sqrt{3}}{2} that means the edges connecting to the apex are a length of 1 each, which I guess is what was also implied by the "regular" pyramid.

Ahhh you are correct. Thanks :smile: