Preheat oven to 350. In a large bowl, combine cooked rice, corn, and blac k beans, and add salsa, cumin, garlic powder, and half the cheese ( 0.75 cup). Spoon mixture into a 8x12x2 inch baking dish coated with cooking spray. Bake, COVERED, about 25 minutes. Remove cover and sprinkle with remaining half of c heese; bake 15 more minutes. Cool 10 minutes and serve.