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Find the value of p which the points (1,2) (p, p) and (-3,-4) are collinear |
Answer» Solution :-Given (1,2) (p, p) and (-3, - 4) are COLLINEAR Here, x₁ = 1, y₁ = 2, x₂ = p, y₂ = p, x₃ = - 3, y₃ = - 4 If the points are collinear Area of the TRIANGLE = 0 ⇒ Area of the triangle = 0 ⇒ 1/2 | x₁(y₂ - y₃) + x₂(y₃ - y₁) + x₃(y₁ - y₂) | = 0 ⇒ x₁(y₂ - y₃) + x₂(y₃ - y₁) + x₃(y₁ - y₂) = 0 ⇒ 1 [p - ( - 4 ) ] + p(-4 - 2) + (-3)(2 - p) = 0 ⇒ 1( p + 4 ) + p(-6) - 3(2 - p) = 0 ⇒ p + 4 - 6p - 6 + 3P = 0 ⇒ - 2p - 2 = 0 ⇒ - 2p = 2 ⇒ p = 2/ - 2 = - 1 Therefore the VALUE of p is -1. |
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