A 600 metres long train is running at the speed of 81 km/hr. If it crosses a platform in 40 seconds, then what is the length of the platform (in metres)?
If the length of a chord of a circle is equal to that of the radius of the circle, then the angle subtended, in radians, at the centre of the circle by chord is
A solid sphere of radius 9 cm is melted to form a sphere of radius 6 cm and a right circular cylinder of same radius. The height of the cylinder so formed is