Question

Tick the correct answer and justify: In $△ABC,Ab=6\sqrt{3}cm,AC=12cm$ and $BC=6cm$. The angle $B$ is:

• A. ${120}^o$
• B. ${60}^o$
• C. ${90}^o$
• D. ${45}^o$

Answer 1

The correct option is C ${90}^o$

$Given$
$AB=6\sqrt{3}$
$AC=12$
$BC=6$
$In\Delta ABC$
$A{B}^2+B{C}^2=A{C}^2$
$\Rightarrow {\left(6\sqrt{3}\right)}^2+6^2={12}^2$
$\Rightarrow 36\left(3\right)+36=144$
$\Rightarrow 108+36=144$
$\Rightarrow 144=144$
$Hence\Delta ABCisrightangledatB$