Q81.The equation of the sphere described on the join of (2, -3, 4) and (-5,6,-7) as diameter is–
Correct answer: 2 2 2/x y z 3(x y z) 56 0
Q82.The equation of the sphere having the circle 2 2 2 x y z 9,x 2y 2z 3 as a great circle is–
Correct answer: None of the above
Q83.The plane 2x 2y z 0 touches the sphere 2 2 2 x y z 2x 4y 2z 3 0 if is equal to–
Correct answer: 12
Q84.The vertex of the cone xy 2yz 3zx 0 is the point:
Correct answer: (0,0,0)
Q85.The pole of the plane x y 5z 3 with respect to the sphere 2 2 2 x y z 9 is–
Correct answer: (3, 3,15)
Q86.The radius of the smallest sphere passing through (1, 0, 0) (0, 1, 0) (0, 0, 1) is:
Correct answer: none of the above
Q87.The pole of the plane 2x + 3y – 4z = 6 with respect to the sphere x2 + y2 + z2 + 2z–5 = 0 is:
Correct answer: None of the above
Q88.The centre and radius of circle (())) ((()) 2 2 2 x 2 y 6 z 4,z 0 − + − + = − + − + = − + − + = − + − + = are respectively:
Correct answer: (2,6,0) and 2
Q89.The vertex of the cone (())) ((()))((())) ((()))((()) 2 x 1 y 3z 2y z x 1 4y 6z 0 − + − + − − + = − + − + − − + = − + − + − − + = − + − + − − + = is:
Correct answer: (1,0,0)
Q90.The number of spheres such that the number of their radical planes is equal to the number of their radical lines in
Correct answer: 5
Q91.The number of independent constants to determine a cone with vertex origin is
Correct answer: 4
Q92.If the cone 2x2 +λy2 -5z2 = 0 has three mutually perpendicular tangent planes, then λ is equal to
Correct answer: −10/3
Q93.Angle between conjugate lines of a sphere is
Correct answer: 90°
Q94.An ellipse cannot be obtained by an intersection of a plane with
Correct answer: sphere
Q95.The angle between the radical plane of two spheres and the line joining their centers is
Correct answer: 900
Q96.If the plane lx + my + nz = p touches the sphere x2 + y2 + z2 = a2 then l2 + m2 + n2 is equal to
Correct answer: 2 p a
Q97.The maximum distance from the point (1, 2, 2) to the surface x2 +y2 +z2 =25 is
Correct answer: 3
Q98.The equation of the sphere of least radius, passing through the pints (a,0,0) (0,a,0) and (0,0,a) is:
Correct answer: () () 2 2 2 2 3 x y z 2a x y z a 0 + + − + + − =
Q99.The equation of the reciprocal cone to the cone fx gy hz 0 + + = + + = + + = + + = is:
Correct answer: fyz+gzx+hxy = 0
Q100.The equation of the sphere which passes through the origin and the points of intersection of plane x y z 1 a b c + + = + + = + + = + + = with the coordinate axes, is
Correct answer: x2 + y2 + z2 – ax – by – cz = 0