Answer
a. No, it is not a right triangle.
b. Yes it is possible.
Work Step by Step
a.
Let the side lengths be $a=20\; mm, b=47\; mm$ and $c=52\; mm$.
We have $a^2+b^2=20^2+47^2=400+2209=2609$.
and $c^2=52^2=2704$.
It does not follow Pythagorean Theorem.
Hence, this is not a right triangle.
b.
The given equation is $a^2+b^2=c^2$.
Replace $a=2a,b=2b$ and $c=2c$
$(2a)^2+(2b)^2=(2c)^2$
Clear the parentheses
$4a^2+4b^2=4c^2$
Divide the equation by $4$.
$a^2+b^2=c^2$.
This is a right triangle, because it follows Pythagorean theorem.
