Atriangular pyramid is cut by a plane. in which case is the cross section a quadrilateral?

when the plane intersects the base and all three lateral faces of the pyramid

Step-by-step explanation:

In order to get a quadrilateral, that is, a polygon with 4 sides, it is necessary that the plane intersect 4 faces of the 3d shape. A triangular pyramid has four faces, a base and three lateral faces. So, the plane have to intersect them all.

= 5

step-by-step explanation:

to find the 15th term substitute n = 15 into the nth term formula

= (- 3 × 15 ) + 50 = - 45 + 50 = 5