Question

What is the perimeter of a triangle if the lengths of the sides are 8", 10", and x?

Answer 1

8^2+10^2=c^2
62+100=c^2
162=c^2
12.73=c

Answer 2

so basically you're trying to find the third side. I'd like you to meet this new equation called the Pythagorean theorem. The equation is basically a²+b²=c².

So here is where you use the formula:

Replace x and y with 8 and 10

8²+10²=c²

Now simplify the equation

8² = 64
10² = 100
64+100=c²
164=c²

now you have to remove that ² from c. So basically you cancel it by square rooting it. But if you square root one side, you have to square root the other side.

√164 = √c²
√ and ² cancel each other out...
c = √164
√164 = 12.8
c= 12.8

Wait! we're not done yet cause now you have to find the perimeter of the triangle.

12.8+8+10
=30.8
Hope this helps!