Question

If A(5,8), B(-3,4), C(7,k) are vertices of ∆ABC and angle B=900
then k=

Answer 1

Step-by-step explanation:

Area of triangle =

2

1

[

x

1

(y

2

−y

3

)+x

2

(y

3

−y

1

)+x

3

(y

1

−y

2

)

]

=

2

1

[

0(4+9)+0(−9−9)+(−5)(9−4)

]=

2

1

[

−5(5)

]=−

2

25

The negative area cannot be possible.

∴ It must be

2

25

So, option A is correct.