what is the formula to find the area of an isosceles triangle??

Question

base is 229.43 sides 200
angles 35, 35 and 70

thanks!

ohhh yeah sorry, angles are 55, 55 and 70!

Answer 1

Are you sure that the angles are right???
They do not even add up to 180 degrees, i.e. this cannot be a triangle.

In any case, here's a nifty formula to remember.
Simply apply the Hero's/Heron's formula
s
= (sum of all sides)/2
= (229.43 + 200 + 200)/2
Area of triangle
= squareroot (s(s-229.43)(s-200)(s-200))

Answer 2

Actually
the angles does not add upto 180 and a figure drawn with such angles will never form a triangle. Recheck the question.

The area of an isoceless triangle can be found using

A=1/2 * b * (a^2 - [b/2]^2)^ 1/2

where b is the base of the triangle and a is one of the equal sides.
I am not sure whether this formula is correct . Do bring to my attention if this is wrong.

regards Exorcist

Answer 3

Only some of the information is needed. You have revised the angles to 55°, 55°, 70°.

Perhaps the easiest is to use SAS to calculate the area.

Area = (1/2)ab cosC = (1/2)(200)(200)(sin 70°)

Area = 20,000(sin 70°) ≈ 18,793.852

Answer 4

Find the lenght from the middle of the base, by disecting the base using a set of compasses, to the vertex. This is the height of the triangle. Use the general formula for calculating the area of triangle:
0.5XbaseXheight

Answer 5

first. be aware that the angles are superfluous here. second, vertically cut the triangle in half [229.43 divided by 2]. then you take either side of the triangle and find the middle side by using the pythagorean theorem [a squared + b squared = c squared, c being the hypotenuse]. Finally now that you've obtained the missing side, you multiply the base with the height of the triangle and divide it all by 2 like so:

base [229.43] x missing side[u got this from the pythagorean theorem]
-------------------------------
2 .


then u've got your answer :)

Answer 6

(B x H) ٠/٠ 2 = Area of ALL kinds of triangles =]