An isosceles triangle has sides A, B, and C, such that sides A and B have the same length. Side C has a length of #2 # and the triangle has an area of #16 #. What are the lengths of sides A and B?

1 Answer
MathFact-orials.blogspot.com
May 25, 2016

Find the height of the triangle by cutting it in half and making a right triangle, then use the pythagorean theorem to get to sides A and B with lenth
#sqrt(65)#

Explanation:

We have an isosceles triangle with base of 2 and sides A and B. The whole triangle has area of 16. What is the length of a side?

Let's start with the equation for the area of a triangle:

#A=bh#

Let's think about this triangle for a second - what we're trying to find is the length of a side, so either A or B will do. So we don't need to work with the whole triangle. Instead, we really only have to work with 1/2 of the triangle - that would create a right triangle where one base is the height of the whole triangle, another base is 1/2 the base of the whole triangle (and so that measure is 1) and half the area (which would be 8).

We can now figure out the height:

#8=1(h)#

#h=8#

And with that, we can now figure out the sloping side of the whole triangle, which is also the hypotenuse of the right triangle, using the pythagorean theorem:

#a^2+b^2=c^2#

#1^2+8^2=c^2#

#1+64=c^2#

#c=sqrt(65)#

And so sides A and B are length #sqrt(65)#

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