The angles of elevation of the top of a tower 72 metre high from the top and bottom of a building are 30° and 60° respectively. What is the height (in metres) of building?
During the free fall of the object, the decrease in potential energy, at any point in its path, appears as an equal amount of increase in _________________.
Present ages of R and P are in the ratio of 9 : 11 respectively. After 7 years, their ages will be in the ratio of 26 : 31 and sum of their ages will be 114 years. What is the present age (in years) of P?