1.

If the points A (-1,-4), B (b,c) and C (5,-1) are collinear and 2b + c = 4, find the values of b and c.

Answer»

The given points A(−1, −4), B(b, c) and C(5, −1) are collinear. 

Area of the triangle having vertices (x1,y1), (x2,y2) and (x3,y3

\(\frac{1}2\) |x1(y2-y3)+x2(y3-y1)+x3(y1-y2)| 

Given that area of ∆ABC = 0 

∴ −1[c − (− 1)]+b[− 1 − ( − 4)] + 5( − 4 − c) = 0 

∴ − c − 1 + 3b − 20 − 5c = 0 

3b − 6c = 21 

∴b − 2c = 7 …(1) 

Also it is given that 2b + c = 4 …(2) 

Solving 1 and 2 simultaneously, we get, 

2(7 + 2c) + c = 4 

14 + 4c + c = 4 

5c = − 10 

c = − 2 

∴ b = 3 

Hence, 

value of b and c are 3 and -2 respectively



Discussion

No Comment Found

Related InterviewSolutions