Respuesta :

Answer:

45

Step-by-step explanation:

by the definition of an isocoles triangle, defined by having two congruent sides,  (p-s, r-s), angles SPR and SRP are congruent. by the triangle sum theorem, (internal angles + to 180˚) 90˚ + 2a = 180˚. 2a =90, a = 45