

CBSE Class 12th Toppers List 2024
NCERT Solutions Class 12 Maths Chapter 4 PDF Download Link
Solve The Following Questions NCERT Solutions for Class 12 Maths Chapter 4 Exercise 4.3 Determinants
Question 1. Find the area of the triangle with vertices at the points 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) Solution : (i) The area of the triangle with vertices (1, 0), (6, 0), (4, 3) is given by the relation, =
(ii) The area of the triangle with vertices (2, 7), (1, 1), (10, 8) is given by the relation,
=
(iii) The area of the triangle with vertices (−2, −3), (3, 2), (−1, −8)
=
Question 2. Show that the points A(a,b + c), B(b, c + a), C(c, a+b) are collinear.
Solution :
Therefore, points A, B and C 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 )
Solution : We know that the area of a triangle whose vertices are ( x 1 , y 1 ), ( x 2 , y 2 ), and ( x 3 , y 3 ) is the absolute value of the determinant (Δ), where
When −
k
+ 4 = − 4,
k
= 8.
When −
k
+ 4 = 4,
k
= 0.
Hence,
k
= 0, 8.
(ii) The area of the triangle with vertices (−2, 0), (0, 4), (0,
k
) is given by the relation,
∴
k
− 4 = ± 4
When
k
− 4 = − 4,
k
= 0.
When
k
− 4 = 4,
k
= 8.
Hence,
k
= 0, 8.
Hence, the equation of the line joining the given points is
y
= 2
x
.
(ii) Let P (
x
,
y
) be any point on the line joining points A (3, 1) and
B (9, 3). Then, the points A, B, and P are collinear. Therefore, the area of triangle ABP will be zero.
Hence, the equation of the line joining the given points is
x
− 3
y
= 0.
It is given that the area of the triangle is ±35.
Therefore, we have:
⇒ 25 - 5k = ± 35
⇒ 5(5 - k) = ± 35
⇒ 5 - k = ± 7
When 5 −
k
= −7,
k
= 5 + 7 = 12.
When 5 −
k
= 7,
k
= 5 − 7 = −2.
Hence,
k
= 12, −2.
The correct answer is D.
Therefore, option (D) is correct.
| NCERT Solutions for Class 12 Maths Chapter 2 Exercise 2.1 | NCERT Solutions for Class 12 Maths Chapter 2 Exercise 2.2 |
| NCERT Solutions for Class 12 Maths Chapter 2 Miscellaneous Exercise | |
