Question

If the points (0, 1, 2), (2, –1, 3) and (1, –3, 1) are the vertices of a triangle, then the triangle is

• A. Right angled
• B. Isosceles right angled
• C. Equilateral
• D. None of these

Answer 1

Answer: (B)

Isosceles right angled

Answer 2

Here $a = \sqrt { 4 + 4 + 1 } = \sqrt { 9 } , b = \sqrt { 1 + 4 + 4 } = \sqrt { 9 }$ and

$c = \sqrt { 1 + 16 + 1 } = \sqrt { 18 }$.

Obviously it is a right angled and isosceles triangle.