Perimeter of trapezium again

From the figure, $x=18-10=8$ . By the pythagorean theorem , we have

$h=\sqrt{10^2-8^2}=$ $6$

So the perimeter is,

$P=10+10+6+18=$ $\color{#D61F06}\boxed{\large 44}$

From pythagoras theorem, we find the missing side to be 6 and perimeter is 44

By this construction, we can easily apply the Pythagoras theorem.

So the missing side is $\sqrt(10^2 - 8^2) = 6$ . Hence the perimeter

of the figure is $10+10+18+6= 44$ cm