Describe and correct the error in finding the value of x for the triangle shown below.

One side of the triangle is shown as right angle that is$90°$.

Second side of the triangle is given as$2x°$.

Third side of the triangle is given as$x°$.

Sum of all angles of a triangle is$180°$.

The sum of all the angles of a triangle is$180°$.

So, write it as-

$2x{}^{\circ }+x{}^{\circ }+90{}^{\circ }=180°$

Add all the x on the left side of the equation.

$3x{}^{\circ }+90{}^{\circ }=180°$

Subtract $90°$from both the sides.

$3x{}^{\circ }+90{}^{\circ }-90{}^{\circ }=180{}^{\circ }-90°$

In the next step,

$3x{}^{\circ }=90°$

Divide both the sides by 3.

$\frac{3x}{3}=\frac{90}{3}$

This will give the value of $x=30°$

Hence the angle measures are:

First angle is 2x, multiply 2 with 30.

$\begin{array}{l}2x=2\times 30\\ =60\end{array}$

Second angle x, multiply 1 with 30.

$\begin{array}{l}x=1\times 30\\ =30\end{array}$

Third angle is shown as a right angle which is$90°$.

Hence, write the equation as,

$\begin{array}{c}2x°+x°+90°=180°\\ 3x°=90°\\ x=30°\end{array}$

Since all the three sides of the triangle are given, add all the sides and not just two sides.

Hence, the correct equation in finding the value of x is,

$\begin{array}{c}2x°+x°+90°=180°\\ 3x°=90°\\ x=30°\end{array}$