Question

How to I find this? I tried using Pythagorean theorem, but it didn't work

Answer 1

The Pythagorean theorem works.

$12^2+9^2=c^2$
$144+81=c^2$
$225=c^2$
$15=c$

Therefore the perimeter is 12 + 9 + 15 = 36 in. (B)

Answer 2

Then you applied it incorrectly

for a right triangle with legs legnth a and b and hypotonuse c,
a^2+b^2=c^2
hypotonuse=longest side or side oposite right angle



so we see that
hypotnuse=c=unknown
legs are legnth a and b or12 and 9
plug in
a=12
b=9
c=c
a^2+b^2=c^2
12^2+9^2=c^2
144+81=c^2
125=c^2
sqrt both sides
15=c

the legnth of the hypotnuse=15

to find the perimiter, you add all sides up
a+b+c=
12+9+15=
36

answer is 36 inches


B is answer