- #1
Kate2010
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Homework Statement
The area of an equilateral triable is Pi/2.
1) Find the magnitude of its angles
2) Find the length of its sides
3) Find the area of its strict dual
Homework Equations
Area + Pi = sum of 3 angles
cosa=cosbcosc + sinbsinccosu
cosu=cosvcosw + sinvsinwcosa for sides length a,b,c and opposite angles of magnitude u,v,w
The Attempt at a Solution
1) I used the formula involving area, so Pi/2 + Pi = 3(magnitude of angle) so the answer is Pi/2. Assuming equilateral means the same in spherical geometry?
2) I used the cos formula with a=b=c, and the angle is Pi/2, getting to cosa= 0, a=Pi/2, or cosa=1, a=0, so a=Pi/2.
3) Considering the dual triangle to the triangle with sides a, b, c. This dual triangle has sides
Pi − u, Pi − v, Pi − w. So we would get that the triangle has sides length Pi/2 again. So area Pi/2 again? I'm not very convinced about this.