, , and and the acute angle between OQ and OS is

, will result in - 2 marks, as a wrong option is also darkened. Consider a pyramid OPQRS located in the first octant with O as origin, and OP and OR along the x-axis and the y-axis, respectively. The bases OPQR of the pyramid is a square with OP = 3. The point S is directly above the mid-point T of diagonal OQ such that TS = 3. Then the equation of the plane containing the triangle OQS is x - y = 0

and and the length of the perpendicular from P to the plane containing the triangle OQS is

. ONE OR MORE THAN ONE of these four option(s) is(are) correct. • For each question, marks will be awarded in one of the following categories: Full Marks : +4 If only the bubble(s) corresponding to the correct option(s) is(are) darkened. Partial Marks : + 1 For darkening a bubble corresponding to each correct option, provided NO incorrect option is darkened. Zero Marks : 0 If none of the bubbles is darkened. Negative Marks : - 2 In all other cases. • For example, if are all the correct options for a question, darkening all these three will result in +4 marks; darkening only will result in +2 marks; and darkening the perpendicular distance from O to the straight line containing RS is