A tower stands on the top of a building which is 40 metres high. The angle of depression of a point situated on the ground from the top and bottom of the tower are found to be 60 and 45 deg respectively. What is the height (in metres) of tower?

• 20√3
• 30(√3 + 1)
• 40(√3 – 1)
• 50(√3 – 1)