Question

In complex plane the points $1+3i,5+i,3+2i$ are

• A. Vertices of a right angled triangle
• B. Collinear
• C. Vertices of an equilateral triangle
• D. Vertices of an obtuse angled triangle

Answer 1

The correct option is B Collinear

Let the three points be $A(1,3)$ , $B(5,1)$ and $C(3,2)$.

$AB=\sqrt{16+4}=2\sqrt{5}$

$AC=\sqrt{4+1}=\sqrt{5}$

$BC=\sqrt{4+1}=\sqrt{5}$

$AB=AC+BC$

Hence, option B is correct