A mountain is a steep elevated landmass with a height of more than _____ metres.
The height of a mountain is 4255 metres. On rounding off to nearest thousands, the height becomes ______ .
At the foot of a mountain the elevation of its summit is 45∘; after ascending 1000 m towards the mountain up a slope of 30∘ inclination, the elevation is found to be 60∘. Find the height of the mountain.