Find the area of the triangle formed by the lines
y = m1x + c1, y = m2x + c2 and x = 0
Given:
y = m1x + c1 … (1)
y = m2x + c2 … (2)
x = 0 … (3)
Explanation:
In triangle ABC, let equations (1), (2) and (3) represent the sides AB, BC and CA, respectively. Solving (1) and (2):
Thus, AB and BC intersect at B 
Solving (1) and (3):
x = 0, y = c1
Thus, AB and CA intersect at A 0,c1.
Similarly, solving (2) and (3):
x = 0, y = c2
Thus, BC and CA intersect at C 0,c2.
∴ Area of triangle ABC = 
3