3-D Question no. 1 Co-ordinate of a point equidistant from the points (0,0,0) ,(a,0,0) , (0,b,0) , (0,0,c) is looks_one looks_two looks_3 looks_4 (a,b,c) Answer Option looks_3 Solution Solution : is the point which is equidistant from the (0,0,0) ,(a,0,0) , (0,b,0) , (0,0,c). Question no. 2 Let (3,4,-1) and (-1 ,2 ,3 ) are the end points of a diameter of sphere. then the radius of the sphere is equal to looks_one 1 looks_two 2 looks_3 3 looks_4 9 Answer Option looks_3 3 Solution Solution : where x 1 , y 1 , z 1 and x 2 , y 2 , z 2 are the end points of diameters. Now, put the value in the formula . Question no. 3 The equation of the sphere touching the three co-ordinate planes is looks_one x 2 + y 2 + z 2 + 2a( x + y + z) + 2a 2 = 0 looks_two x 2 + y 2 + z 2 - 2a( x + y + z) + 2a 2 = 0 looks_3 x 2 + y 2 + z 2 ± 2a( x + y + z) + 2a 2 = 0 looks_4 None of t...