What is the formula for an isosceles triangle?

Answer 1

An isosceles triangle has two equal interior angles, and two sides whose lengths are equal. If you can prove that at least two of the angles or at least two of the side lengths are equal, then you have proved that the triangle is isosceles. Also, an equilateral triangle must be isosceles, but the reverse is not necessarily true. (There are infinitely many more non-equilateral isosceles triangles than there are equilateral isosceles triangles.) There aren't any special formulas for isosceles triangles that I am aware of. Well, you can use the Pythagorean theorem to find its height if you wish. The formula for the height would be:
h = sqrt(((length of base)/2)^2 + (length of another side)^2)
And because you can find the height, you can also easily find the area. There is another method called Heron's area formula to find the area of any triangle knowing only the sides, but the calculation is more intense than this. If you can determine that a triangle is an isosceles triangle, it is preferable that you use the properties of isosceles triangles (and trigonometry, if necessary, but you probably won't need to know that for a while) to find the height and area because it's much easier overall. I hope this helps!

Edit: (OK, I think I have fixed all the errors now. I just woke up not too long ago, so I'm still in a daze. Enjoy!)

Answer 2

Area=1/2xbasexheight

Answer 3

1/3 X Base X Height

Answer 4

if you are looking for the formula for area it is 1/2 x Base x Height

Answer 5

isoscelas triangle: 1/2 x height x base

Answer 6

Which formula (area, height, etc.)?

Two sides have the same length, and the third side can be any length. If the third side happens to be the same length as the other two sides, it is also equilateral.

Answer 7

http://mathforum.org/dr.math/faq/formulas/faq.triangle.html#isosceles

Answer 8

It has no special formulas, only its definition:
the three sides are equal.
Of course there is a lot of symmetry.