In △ ABC, if O is the intersection of three bisectors and ab: BC: CA = 3:4:6, then the area ratio of △ AOB, △ BOC and △ COA is?

In △ ABC, if O is the intersection of three bisectors and ab: BC: CA = 3:4:6, then the area ratio of △ AOB, △ BOC and △ COA is?

The ratio of area is the ratio of bottom
Because the three bisectors intersect at O, so o is the center of gravity, so the heights are equal. Therefore, the area ratio of △ AOB, △ BOC and △ COA is 3:4:6
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If n is a natural number, prove the integral n (2n + 1) - 2n (n-1)
Please give me the answer quickly
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n(2n+1)-2n(n-1)
=2 times the square of N + n-2 times the square of N + 2n
=3n
3N is divisible by 3
So, n (2n + 1) - 2n (n-1) must be a multiple of 3

Among the four numbers 2004200520062007, the number that cannot be expressed as the square difference of two integers is ()
A. 2004B. 2005C. 2006D. 2007

Because A2-B2 = (a-b) (a + b), 2004 = 5022-50022005 = 10032-100222007 = 10042-10032, and 2006 = 2 × 1003, the parity of A-B and a + B is the same, 2 × 1003 is odd and even, so 2006 cannot be expressed as the square difference of two integers