In a , 2ac is equal to
a2 + b2 - c2
c2 + a2 - b2
b2 - a2 - c2
c2 - a2 - b2
B.
c2 + a2 - b2
The straight line 3x + y divides the line segment joining the points (1, 3) and (2, 7) in the ratio
3 : 4 externally
3 : 4 internally
4 : 5 internally
5 : 6 externally
If the sum of distances from a point P on two mutually perpendicular straight lines is 1 unit, then the locus of P is
a parabola
a circle
an ellipse
a straight line