Question 1: The backward extension line of the two reflected rays O 1B, O2B' is the luminous point S.

Question 2: Yes! ∠b=45. Because A = 50, the included angle between the first incident ray and the reflected ray is 80. ∠ BAC = 50。 Similarly, BCA = 40. ∠ ABC = 180-50-40 = 90。 ∠ B。