A family consists of a grandfather, m sons and daughters and 2n grand children. They are to be seated in a row for dinner. The grand children wish to occupy the n seats at each end and the grandfather refuses to have a grand children on either side of him. In how many ways can the family be made to sit.
A train is going from London to Cambridge stops at 12 intermediate stations. 75 persons enter the train after London with 75 different tickets of the same class. Number of different sets of tickets they may be holding is:
The ends A , B of a fixed straight line of length ‘a’ and ends A¢ and B¢ of another fixed straight line of length ‘b’ slide upon the axis of X & the axis of Y (one end on axis of X & the other on axis of Y). Find the locus of the centre of the circle passing through A, B, A¢ and B¢.
A circle of constant radius ‘r’ passes through origin O and cuts the axes of coordinates in points P and Q, then find the equation of the locus of the foot of perpendicular from O to PQ.
The curves whose equations are
S = ax2 + 2hxy + by2 + 2gx + 2fy + c = 0
S¢ = a¢x2 + 2h¢xy + b¢y2 + 2g¢x + 2f¢y + c¢ = 0
intersect in four concyclic points then find relation in a, b, h, a¢, b¢, h¢.
Let S1 be a circle passing through A(0, 1), B(–2, 2) and S2 is a circle of radius
units such that AB is common chord of S1 and S2. Find the equation of S2.
A triangle has two of its sides along the axes, its third side touches the circle x2 + y2 - 2 ax - 2 ay + a2 = 0. Find the equation of the locus of the circumcentre of the triangle.
Let circles S1 and S2 of radii r1 and r2 respectively (r1 > r2) touches each other externally. Circle S radii r touches S1 and S2 externally and also their direct common tangent. the triangle formed by joining centre of S1, S2 and S is
Let ABCD is a rectangle. Incircle of DABD touches BD at E. Incircle of DCBD toches BD at F. If AB = 8 units, and BC = 6 units, then find length of EF.
Find the equation of the circle which cuts each of the circles, x² + y² = 4, x² + y² - 6x - 8y + 10 = 0 & x² + y² + 2x - 4y - 2 = 0 at the extremities of a diameter.


