If two sides of a triangle are 9 cm and 15 cm in length, which COULD be the measure of the third side?

1 Answer
Mar 22, 2018

There are 2 possible answers to this:

Explanation:

The 9cm for sure is one of the triangle's legs, or one of the short sides, but the 15cm length could be a leg or a hypotenuse

So let's say that the 15 cm one is the hypotenuse, or the longest side of the triangle. We can use the pythagorean theorem of #a^2+b^2=c^2#
Since the 15 cm one is the hypotenuse, that would make it the C value, and the 9 cm one the A or B value, depending on the one you would like. To solve for the missing value, we can do this if A is the 9cm
#9^2+b^2=15^2#
if we were to solve this by isolating the b value: #b^2=15^2-9^2# we would get #b=12 cm#

The other option we had is both the 15 and 9 cm long segments are legs, or the shorter sides. Then to find the long side, or C, we can simply do #9^2+15^2=c^2#, which when solved, we get #c=17.493 cm#