This is a pentagon, with five equal central angles. Each central angle is 360 degrees/5 = 72 degrees.
The pentagon has five pie-shaped pieces, each with an angle of 72 degrees and two other angles, which are equal, of 54 degrees.
The "base" of each such triangular (pie-shaped) pieces is 5.
Use this info to find the area of ONE of these pieces.
Then multiply your result by 5 to obtain the total area of this pentagon.