# Thread: Applying the pythagoren theorem

1. ## Applying the pythagoren theorem

hi im in grade 8 and i need help with a question. A sloped mountain road is 12.7 km long. it covers a horizontal distance of 8.9m. What is the change in the elevation of the road?

I know the the formula and stuff but my teacher told me that since the units arent the same it will affect the pythagorean theorem.

so that confuses me. so can anybody help me figure this out.

2. Originally Posted by so774
hi im in grade 8 and i need help with a question. A sloped mountain road is 12.7 km long. it covers a horizontal distance of 8.9m. What is the change in the elevation of the road?

I know the the formula and stuff but my teacher told me that since the units arent the same it will affect the pythagorean theorem.

so that confuses me. so can anybody help me figure this out.
You can change the units so that they are equal and then use Pythagoras Theorem.

As 1km = 1000m you can either change 12.7km into 12,700m or 8.9m into 8.9*10^-3km and then use Pythagoras.

Either way should give you an answer of 12.7km (=12,700m) (3sf). Note that in this case the answer is virtually the same as the slope. This is because the slope is much bigger than the horizontal distance and so 8.9^2 is negligible compared to 12,700^2

3. for the theorem to work all units must be the same right?

so either change your 12.7km to 12700m and then use the formula or change your 8.9m to 0.0089 km

then try it and see what you get.

also, does your teacher want it in km or m? if he/she wants it in a certain value, then convert it to that