How do I find the area of an isosceles triangle with.a base that is 20 m long and each of the other two sides is 26 m?
Use the formula
You need to find the height of the triangle, so split the isosceles into 2 right angled triangles.
So, one newly- created right angled triangle will have a base length of half of the original triangle, which is
The new base length of the right- angled triangle is
You know the length of the hypotenuse is
So the height of the triangle is
Substitute everything in the formula again.