Question

The triangle ABC has $AB=5cm,AC=8cm$ and $BC=9cm$, then $\Delta ABC$ is

• A. obtuse angled
• B. acute angled
• C. right angled
• D. none of these

Answer 1

The correct option is B acute angled

Let $a=5cm,b=8cm$ and $c=9cm$

We know if $a^2+b^2>c^2$ where $c$ is the longest side of triangle then the triangle is acute angled.

Here $c^2={\left(9\right)}^2=8$

$a^2+b^2={\left(5\right)}^2+{\left(8\right)}^2=89\Rightarrow a^2+b^2>c^2$

So triangle is acute angled.

Hence option $B$ is correct.