1) isosceles triangle
2) equilateral triangle
3) right-angled triangle
4) None of these
Solution: Option (3) Right angled triangle
Given that, P(2, 7) Q (4, – 1) and R (- 2, 6)
The distance between PQ = √68
The distance between PR = √17
The distance between QR = √85
Therefore, PQ2 +PR2 = QR2
(√68)2 + (√17)2 = (√85)2
68+17 = 85
85 = 85
Hence, the triangle joining the points P(2, 7) Q (4, – 1) and R (- 2, 6) is a right angled triangle.
