\(a^2=b^2+c^2\)
\(a^2=17^2+8.5^2\)
You'll have to use whatever method you prefer for multiplication without calculator. I like to use this method.
\(a^2=289+72.25\)
\(a^2=361.25\)
\(a=\sqrt{361.25}\)
This is an answer for root form. To convert it to decimal, we can do some trial and error.
\(20^2=400\)
\(19^2=361\)
That's probably the closest we're going to get, so we give the decimal answer as:
\(a\approx19\)
.