Question 444084
I do not believe any answer is correct, b would work if you were using the height instead of side c.

I do not believe we could find the height unless we know which angle is the 30 degree angle.

I did find, however a formula for finding the height of an isosceles triangle using the sides without the angles that should work.

h = sqtr of ( c^2 - 1/4( b - a)^2 )


This was obtained from http://mathworld.wolfram.com/IsoscelesTrapezoid.html


If this value is replaced for c in choice b, that should give your result.

Cleomenius.