### Coordinate Geometry - Circle

*For 1, find the standard form of the equation of the specified circle. 1. Endpoint of a diameter, (-4,-1), (4, 1) *For 2~4, write the given equation of the circle in standard form and sketch its graph. 2. X^2 + Y^2 -2X + 6Y - 15 = 0 3. 3X^2 + 3Y^2 - 6Y -1 = 0 4. 4X^2 + 4Y^2 -4X + 2Y -1