Concept:When two plane mirrors are inclined at an angle θ, the number of images formed is given by θ360∘−1.Explanation:The mirrors are placed at an angle θ=90∘.Substitute into the formula: n=90∘360∘−1.Calculate: 90∘360∘=4.Then subtract 1: n=4−1=3.Therefore, three images are formed when an object is placed between the two mirrors.Answer:3 images are formed.