when n = 2 , L H S : n ! = 2 ! = 2x1 = 2 RHS:
But if n = 1 , the inequation does not hold good.
The equation represents
The general equation of the circle is x2+y2-2gh-2fy+c = 0. Sice the given equations satisfies the general equation, it represents the equation of the circle.
No: of combinations of n different things taken r at at a time is given by nCr
No: of combinations of n different things taken r at a time and excluding m particular things is n - mCr = C(n-m,r)
where l,m,n represent direction cosineIn a (b +c) cos A + (c + a) cos B + (a + b) cos C is equal to

, are