Question 487059: Hello,
I would like a formula that will solve for the base length of an isosceles triangle. I have an excel application that generates a vertex angle and a height, but I have been unable to figure out how to calculate the length of the base based upon those two values.
What I have found on the net has been too confusing for me to apply, so I am hoping someone can walk me through it.
Thank you,
Mike
Answer by cleomenius(959)   (Show Source):
You can put this solution on YOUR website! You can draw angle bisector from the vertex, which you have been given.
This will create two congruent triangles, since the triangle is isosceles.
The side opposite this vertex will be connected at its midpoint by the segment that is formed from the angle bisector.
You can then determine the side opposite the half of the vertex angle by the tangent function, tan 1/2 vertex angle = opposite length/adjacent length (height);
this will be half of your base.
The formula will be in terms of base:
2 ((tan 1/2 vertex angle ) * adjacent angle.)
Cleomenius.
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