6. a.An object 4 cm in size is placed at a distance of 25 cm from a concave mirror of focal
length 15 cm. Find the position, nature and height of the image.
b A converging mirror forms a real image of height 4 cm, of an object of height 1 cm
placed 20 cm away from the mirror. Calculate the image distance. What is the focal
length of the mirror?