मराठी

Find the value of k, if the area of the triangle with vertices at A(k, 3), B(–5, 7), C(–1, 4) is 4 square units. - Mathematics and Statistics

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प्रश्न

Find the value of k, if the area of the triangle with vertices at A(k, 3), B(–5, 7), C(–1, 4) is 4 square units.

बेरीज

उत्तर

Here, A(x1, y1) ≡ A(k, 3), B(x2, y2) ≡ B(– 5, 7), C(x3, y3) ≡ C(– 1, 4)
A(ΔABC) = 4 sq. units

Area of a triangle = `1/2|(x_1, y_1, 1),(x_2, y_2, 1),(x_3, y_3, 1)|`

∴ `1/2|("k", 3, 1),(-5, 7, 1),(-1, 4, 1)|` = ± 4

∴ k(7 – 4) – 3(– 5 + 1) + 1(– 20 + 7) = ± 8
∴ 3k + 12 – 13 = ± 8
∴ 3k – 1 = ± 8
∴ 3k – 1 = 8 or 3k – 1 = – 8
∴ 3k = 9 or 3k = – 7

∴ k = 3 or k = `(-7)/3`

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Application of Determinants - Area of a Triangle Using Determinants
  या प्रश्नात किंवा उत्तरात काही त्रुटी आहे का?
पाठ 6: Determinants - EXERCISE 6.3 [पृष्ठ ९३]

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