Let A(h,k), B(1,1) and C(2,1) be the vertices of a right angled triangle with AC as its hypotenuse. If the area of the triangle is 1, then the set of values which 'k' can take is given by
(A){1,3}
(B){0,2}
(C){−1,3}✓ Correct
(D){−3,−2}
Answer: (C)
Solution
With AC the hypotenuse, the right angle sits at B(1,1). Since B and C(2,1) share the same height, BC is horizontal of length 1, so the right angle at B forces BA to be vertical, placing A at (1,k). The area 21⋅1⋅∣k−1∣=1 gives ∣k−1∣=2, so k=3 or k=−1.
JEE Main · 2007 · 29 Apr 2007 · Offline · Single correct option