Radius of a circle inscribed in an isosceles trapezoid

Details

radius circle inscribed trapezoid

a black  -  upper base

b black  -  lower base

h   -  height of a trapezoid

O black  - circumcenter    

 

Calculate the radius of a inscribed circle in an isosceles trapezoid if given height or bases ( r  ) :

radius circle inscribed trapezoid F