Then you also know that a triangle has 3 sides but the book only gives you 2. So you know there is at least one variable, in this case, we’ll use X. The other two given sides are 3 and 4. And since you know that a triangles perimeter is the sum of all 3 sides. So the 3 sides are 3, 4 and x. Then we also explained before that the perimeter equals 12.

So the 3 points, 3, 4 and x all have to equal 12. Therefore….

3 + 4 + X = 12

Now you solve

1) combine all the same terms (add the numbers)

7+X=12

2) Now we need to get X alone, we can do that by subtracting 7 from both sides therefore…

X+7 – 7 =X

12 – 7 =5

Therefore the answer is X=5

Put in the unit to get 5 feet.

a^2 + b ^2= c^2

3^2 +4^2 = c^2

9+ 16=c^2

9+16 = 25

Now You Do The Square Root Of 25

X=5

Or You Can Just Add 3 And 4

Which Is 7 And Say 7+X = 12 Since 12 Is The Perimeter Of The Trangle

7+X=12

-7 -7

The 7 Cancels Out Becasue The Same Negative + Same Postive Is 0. Then You Do 12-7 Because You Had To Move The 7 To The Other Side In Order To Get X Alone.

12-7=5

X=5

so 3 and 4 are the legs of the triangle. and the perimeter of it is all the sides. SO x+3+4=12…x+7+12…..x=5

the perimeter is 12 so we set up an equation…

a+b+c=12

one leg is 3, one is 4 so we plug those in…

3+4+c=12

3+4 is 7

then 12-7 = c

c= 5