The coefficient of static friction between the 3000-lb car’s tires and the road is μs= 0.5...

The coefficient of static friction between the 3000-lb car’s tires and the road is μs= 0.5. Determine the steepest grade (the largest value of the angle α) the car can drive up at constant speed if the car has (a) rear-wheel drive; (b) front-wheel drive; (c) four-wheel drive.