Answer:
Half of 40 is 20(new radius)
20^2 = 400
400 x 3.14 = 1256 meters^2
Formula of area of a circle:
πr2
pi(3.14 or 22/7 whatever they tell you to use for pi) x radius(half of your diameter or your given radius) being squared(^2 to the power of 2)
