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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 |
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