# Summary

1. The distance between P(x1, y1) and Q(x2, y2) is .
2. The distance of a point P(x, y) from the origin is .

3. The coordinates of the point P(x, y) which divides the line segment joining the points A(x1, y1) and B(x2, y2) internally in the ratio m1: m2 are .

4. The coordinates of the point P(x, y) which divides the line segment joining the points A(x1, y1) and B(x2, y2) externally in the ratio m1: m2 are

5. The mid-point of the line segment joining the points P(x1, y1) and Q(x2, y2) is .

6. The area of the triangle formed by the points(x1, y1), (x2,y2) and (x3, y3) is the numerical value of the expression .

7. Three given points are said to be collinear if the area of the triangle is zero.