Question

A triangle with vertices (4, 0), (-1, -1), (3, 5) is

• A. Isosceles and right angled
• B. Isosceles but not right angled
• C. Right angled but not isosceles
• D. Neither right angled nor isosceles

Answer 1

The correct option is A

Isosceles and right angled

Let A(4, 0), B(-1, -1), C(3, 5) then AB = $\sqrt{26}$, AC = $\sqrt{26}$ and BC = $\sqrt{52}$ i.e., AB = AC.

Hence triangle is isosceles. Also, $(BC{)}^2$ = $A{B}^2+A{C}^2$

Hence triangle is right angled also.