Question
Question: If (x<sub>i</sub>, y<sub>i</sub>) , i = 1, 2, 3 are vertices of equilateral triangle such that (x<su...
If (xi, yi) , i = 1, 2, 3 are vertices of equilateral triangle such that (x1 + 2)2 + (y1 – 3)2 = (x2 + 2)2 + (y2 –3)2
= (x3 +2)2 + (y3 –3)2 then value of y1+y2+y3x1+x2+x3 is:
A
32
B
–32
C
23
D
–23
Answer
–32
Explanation
Solution
From given condition we can say circumcentre is point (– 2, 3)
but triangle is equilateral so centroid is (– 2, 3)
Ž 3x1+x2+x3 = – 2, 3y1+y2+y3 = 3
Ž y1+y2+y3x1+x2+x3 = – 32