Here's how to figure out the number of images formed by two plane mirrors tilted at an angle:

The Formula

The number of images (N) formed by two plane mirrors inclined at an angle (θ) is given by:

N = 360°/θ - 1

Calculation

1. Substitute the angle: In this case, θ = 72 degrees.

2. Calculate: N = 360°/72° - 1 = 5 - 1 = 4

Answer:

Therefore, four images are formed when two plane mirrors are tilted at an angle of 72 degrees.