Answer :
theta = 50 degrees
Solution:
angle of incidence = reflection angle.
so,
angle of incidence = 90 - [180- 70 - (90-b) ]
= 70 - b
reflection angle = b+20.
b+20 = 70
b= 70-20
b=50 degrees
Solution:
angle of incidence = reflection angle.
so,
angle of incidence = 90 - [180- 70 - (90-b) ]
= 70 - b
reflection angle = b+20.
b+20 = 70
b= 70-20
b=50 degrees