What is the area, in square feet, of an isosceles triangle whose vertex angle is 120 and whose base is 20 feet long? Express your answer as a common fraction in simplest radical form.

If you decide to help, I appreciete it

Guest Jul 25, 2019

#1**+2 **

it seems i am the only one on so ill try but i do not know what the vertex angle is can you infom me on that?

travisio Jul 25, 2019

#5**+6 **

Draw a height from the base to create two congruent 30-60-90 triangles.

the side across from the 60° angle = 10

the side across from the 30° angle = 10/√3

area of isosceles triangle = ( 1/2 )( base )( height )

area of isosceles triangle = ( 1/2 )( 20 ft )( 10/√3 ft )

area of isosceles triangle = 100 / √3 square feet

area of isosceles triangle = 100√3 / 3 square feet

hectictar Jul 25, 2019