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Exercise - 4.3

Determinants

**Question-1 :-**
Find area of the triangle with vertices at the point given in each of the following :

(i) (1, 0), (6, 0), (4, 3)

(ii) (2, 7), (1, 1), (10, 8)

(iii) (–2, –3), (3, 2), (–1, –8)

(i) Hence area of triangle = 15/2 square unit

(ii) Hence area of triangle = 47/2 square unit

(iii) Hence area of traingle = 15 square unit

**Question-2 :-**
Show that points A (a, b + c), B (b, c + a), C (c, a + b) are collinear.

**Question-3 :-**
Find values of k if area of triangle is 4 sq. units and vertices are

(i) (k, 0), (4, 0), (0, 2)

(ii) (–2, 0), (0, 4), (0, k)

(i)

(ii)

**Question-4 :-**
(i) Find equation of line joining (1, 2) and (3, 6) using determinants.

(ii) Find equation of line joining (3, 1) and (9, 3) using determinants.

(i)

(ii)

**Question-5 :-**
If area of triangle is 35 sq units with vertices (2, – 6), (5, 4) and (k, 4). Then k is

(A) 12 (B) -2 (C) -12,-2 (D) 12,-2

The correct answer is D.

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