ΔABC is similar to ΔDEF. Length of AB is 12 cm and length of the corresponding side DE is 8 cm. What is the ratio of Perimeter of ΔABC : Perimeter of ΔDEF?
From the top of a building, the angles of elevation and depression of top and bottom of a tower are 60 deg and 30 deg respectively. If the height of the building is 5m, then the height of the tower is