Find the power of a convex lens if the image formed is at a distance of 25 cm from the lens when the object is placed on the other side of the lens at 12 cm from the optical centre?
Smaller diagonal of a rhombus is equal to length of its sides. If length of each side is 6 cm, then what is the area (in sq.cm) of an equilateral triangle whose side is equal to the bigger diagonal of the rhombus?