91Ó°ÊÓ

It is given that one angle of a triangle is $30°$more than the smallest angle and the largest angle is the sum of the other angles.

The objective is to find the measures of all three angles.

Let the measure of the smallest angle be $x°$.

Now the second angle is $30°$more than the smallest angle so it is given as $x°+30°$.

Also the largest angles is sum of the other two angles so it is given as$x°+x°+30°=2x°+30°$.

It is known that the sum of the measure of all three angles of a triangle is $180°$.

So the sum of $x°$, $x°+30°$, and $2x°+30°$is equal to $180°$

$\begin{array}{rcl}x°+x°+30°+2x°+30°& =& 180°\\ 4x°+60°& =& 180°\\ 4x°& =& 180°-60°\\ 4x°& =& 120°\end{array}$

Divide both sides by $4$.

$\begin{array}{rcl}\frac{4x°}{4}& =& \frac{120°}{4}\\ x°& =& 30°\end{array}$

The measure of the smallest angle is $30°$.

The measure of the second angle is

$\begin{array}{rcl}x°+30°& =& 30°+30°\\ & =& 60°\end{array}$

And the measure of the largest angle is

$\begin{array}{rcl}2x°+30°& =& 2×30°+30°\\ & =& 60°+30°\\ & =& 90°\end{array}$