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
+799 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?
+9481 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
