A ray of light is incident at `50^(@)` on the middle of one of the two mirrors arranged at an angle of `60^(@)` between them. The ray then touches the second mirror, gets reflected back to the first mirror, making an angle of incidence .....:

Options

A. `50^(@)`
B. `60^(@)`
C. `70^(@)`
D. `80^(@)`

Answer

C

Explanation

let required andlg be ` theta.`

In `Delta ABC,`
`90^(@) 0 thea + 140 ^(@) + 20^(@) = 180^(@)`
`implies theta = 70^(@)`