What should be done when Ketu is exalted in the 2nd house and the house has a North-East cut?

Put the mirror for the zone that is missing. Fixed so that it works from inside towards outside, it extends and enlarges that missing space.

No. Wardrobe mirrors also belong on the North or East wall. Some say the North-West is also allowed because the mirror represents the water element and the Moon.

Fix it on the inside of the wall of the part you want to extend; seen from inside, that portion looks bigger and is extended. Fixing it on the outer side makes that part look smaller, so the outer side is used only when a part must be reduced.

Mark it the usual way: find the centre and north, place the chakra on the centre and mark the devtas. To divide the bands, take every corner of the shape, draw lines from the centre to each, apply the ratios and join the points; a similar shape forms inside. The more irregular the shape, the more complicated the work, and software makes it easier.

A plain mirror shows about three times its size, as a 2 ft mirror shows a 6 ft person. For a 10 to 12 ft area with a 12 ft cut, use at least a 2.5 to 3 ft mirror; even a 1 ft mirror works to some extent, but the result depends on the area and the mirror quality. Use a convex mirror to enlarge a cut and a concave mirror to reduce an extension.

No. The darpan is considered auspicious and is used even in pooja; do not replace it with plastic films.