Mirror equation or

mirror formula







As incident angle is equal to the reflected angle,



So     < APB  =  <A'P B'



So,      





therefore,        








    

Again     <ACB  =  <A'CB'



So,      






therefore







therefore from 9.21 and 9.12







Now according to cartesian sign convention


Object distance = BP = -u

Radius of curvature = CP = -R

Image distance = B'P = -v



















But we know that R = 2f






And these following two are the mirror formula