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eroshea
An isosceles triangle ABC, in which AB=BC=6 root 2 and AC=12 is folded along the altitude BD so that planes ABD and BDC form a right dihedral angle. Find the angle between side AB and its new position.
could you draw a bit of figure?
i can't .. that is my problem, too..
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so what i'm going to find is the theta??
Find the angle between side AB and its new position. what does this mean?
i guess that's the angle you are going to find ... can you find it?
i need further solution/explanation
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\( \theta \) will be half of \( \alpha \)
the book's answer is 60 degrees.. but i find it 45 degrees.. how did it ended up with 60?
yep .. should be around like that if you did it properly!!
aawww. can you explain it ?
looks like you did it right http://www.wolframalpha.com/input/?i=12^2+%3D+2%286+sqrt%282%29%29^2+-+2+*+%286+sqrt%282%29%29^2+cos%28x%29
b^2 = a^2 + c^2 - 2ac cos theta that is cosine law right? and the answer is 90 degrees