Answer
$\frac{\sqrt{15}}{4}$
Work Step by Step
In order to use Heron's Formula we have to find the semiperimeter:
$s=\frac{1}{2}(a+b+c)$
$s=\frac{1}{2}(1+2+2)$
$s=\frac{1}{2}*5$
$s=\frac{5}{2}$
We can use Heron's Formula from here:
$A=\sqrt{s(s-a)(s-b)(s-c)}$
$A=\sqrt{\frac{5}{2}(\frac{5}{2}-1)(\frac{5}{2}-2)(\frac{5}{2}-2)}$
$A=\sqrt{\frac{5}{2}*\frac{3}{2}*\frac{1}{2}*\frac{1}{2}}$
$A=\sqrt{\frac{15}{16}}$
$A=\frac{\sqrt{15}}{4}$
$A\approx 0.97$
