Can a brick witch measures 9cm by 12cm by 25cm pass down a cylindrical pipe of diameter 14cm

Yes: if you lay the brick so that the 25cm side is vertical, the brick is lying on a 9x12 rectangle, which fits inside a 14cm circle.

So, the 25cm side will be parallel to the cylinder's height, and the brick can pass

last option

step-by-step explanation:

given that δdef is right and isoceles,

assuming that side df is the hypotenuse means that de an ef are the other 2 sides that intersect at 90° and are of equal length.

because they are of equal length, we can say that they are congruent

because they intersect at 90°, their slopes must be opposite reciprocals.

only the last option satisfies these conditions.

there are infinitely many solutions.