NCERT Solutions
Class 12 - Mathematics Part-1 - Chapter 4: DETERMINANTS
Exercise 4.2

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) \((-2,-3), (3,2), (-1,-8)\)

Answer:

(i) \(\frac{15}{2}\)

(ii) \(\frac{47}{2}\)

(iii) 15

Question. 2

Show that points \(A(a, b+c),\; B(b, c+a),\; C(c, a+b)\) are collinear.

Answer:

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) \((-2,0), (0,4), (0,k)\)

Answer:

(i) \(k = 0,\; 8\)

(ii) \(k = 0,\; 8\)

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.

Answer:

(i) \(y = 2x\)

(ii) \(x - 3y = 0\)

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

Answer:

(D)

NCERT Solutions Class 12 – Mathematics Part-1 – Chapter 4: DETERMINANTS – Exercise 4.2 | Detailed Answers