If the three angles in a triangle are in the ratio $1:2:3$, then the largest angle is

Given three angles in a triangle are in the ratio is $=1:2:3$

$=x:2x:3x$

Since in a triangle the sum of three angles is $180°$

i.e. $\overline{)A}+\overline{)B}+\overline{)C}=180°$

$x+2x+3x=180°$

$6x=180°$

$x=30°$

$\therefore$$\overline{)A}=x=30°$

$\overline{)B}=2x=2(30°)=60°$

$\overline{)C}=3x=3(30°)=90°$