(Please help, I don't understand) Use the distance formula to find the distance between each pair of points:

Step-by-step explanation:
Distance = √(x_2 - x_1)² + (y_2 - y_1)²
Distance = √[(-a) - a]² + (b - b)²
Distance = √[-2a]² + (0)²
Distance = √4a²
Distance = 2a