Notice below the picture
the one on the left-hand-side, is the 30-60-90 rule
those are the ratios, for 16), the hypotenuse (slanted side), is 4
for the ratios, that means that 4 = 2x, if you solve that for "x", that simply means "x" is 2
now, just use that value you found for "x" from the hypotenuse ratio, and use it to get the other two sides
what's the perimeter? all three sides added together
for 17)