The question you are asking is a circle with shaded portion and a portion not shaded . The radius of the circle is given as 13 yards . H is the center of the circle and unshaded part of the the sector has an angle of 126°.
The area of a sector = ∅/360 × πr²
The other angle of the shaded portion is unknown . To find the angle we subtract 126° from 360°(complete angle).