# Two sides of a triangle have lengths 10 and 15 what must be true about the length of the third side

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Consider the triangle. A triangle has angle measures of 45 degrees, 45 degrees, and 90 degrees. Which statement is true about the lengths of the sides? Each side has a different length. Two sides have the same length, which is less than the length of the third side. The three sides have the same length. The sum of the lengths of two sides is equal to the length of the third side.

Two sides of a triangle have lengths

and
. The length of the altitude to the third side is the average of the lengths of the altitudes to the two given sides. How long is the third side?

## Solution 1 (Process of Elimination)

The shortest side length has the longest altitude perpendicular to it. The average of the two altitudes given will be between the lengths of the two altitudes, therefore the length of the side perpendicular to that altitude will be between

and
. The only answer choice that meets this requirement is
.

## Solution 2

Let the height to the side of length

be
, the height to the side of length 10 be
, the area be
, and the height to the unknown side be
.

Because the area of a triangle is

, we get that
and
, so, setting them equal,
. From the problem, we know that
. Substituting, we get that
Thus, the side length is going to be
.

Let be the height of triangle when the base is

and is the height of the triangles when the base is
. This means the height for when the triangles has the rd side length, the height would be
giving us the following equation:

For , we can plug in the answer choices and check when the ratio of
for
and
is the same because we can observe that only for one value, the ratio remains constant. From brute force we get that
meaning that
is the rd base. ~ Batmanstark

## Video Solution

https://youtu.be/27TpizTnMeM

~savannahsolver