2
Question
The area of a triangle with vertices (-3,0), (3,0) and (0,k) is 9 sq. units. The value(s) of k is/are:
The area of a triangle with vertices (-3,0), (3,0) and (0,k) is 9 sq. units. The value(s) of k is/are:
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Solution
The correct options are
A 3
B -3
We know that area of triangle whose vertices are
(x1, y1), (x2, y2), (x3, y3) is given by
=⎛⎜⎝12⎛⎜⎝x1y11x2y21x3y31∣∣
∣
∣∣∣∣
∣
∣∣⇒⎛⎜⎝12⎛⎜⎝−3013010k1∣∣
∣∣∣∣
∣∣=9⇒−3(−k)−0+1(3k)=±18⇒6k=±18⇒k=±3
A 3
B -3
We know that area of triangle whose vertices are
(x1, y1), (x2, y2), (x3, y3) is given by
=⎛⎜⎝12⎛⎜⎝x1y11x2y21x3y31∣∣ ∣ ∣∣∣∣ ∣ ∣∣⇒⎛⎜⎝12⎛⎜⎝−3013010k1∣∣ ∣∣∣∣ ∣∣=9⇒−3(−k)−0+1(3k)=±18⇒6k=±18⇒k=±3