Question

find the are of the triangle whose vertices are (-2,-3),(3, 2)and (-1,8) using determinants in 2nd puc mathematics

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Answer 1

Step-by-step this is the way to solve this

Answer 2

Answer:

Area of triangle is

△=

2

1

∣

∣

∣

∣

∣

∣

∣

∣

x

1

x

2

x

3

y

1

y

2

y

3

1

1

1

∣

∣

∣

∣

∣

∣

∣

∣

where (x

1

y

1

)=(−2,−3);(x

2

y

2

)=(3,2);(x

3

,y

3

)=(−1,−8)

∴△=

2

1

∣

∣

∣

∣

∣

∣

∣

∣

−2

3

−1

−3

2

−8

1

1

1

∣

∣

∣

∣

∣

∣

∣

∣

Expanding △ using R

1

(first row)

△=

2

1

[−2(2+8)+3(3+1)+1(−24+2)]

=

25

1

[−20+12−22]=

2

1

∣−30∣=

2

30

△=15 sq.units.