Question

in a circular garden of diameter 150m a pond is constructed in the form of circle with radius 20m find the area of the land left out

Answer 1

area left=area of garden -area of pond
22/7x75x75 _22/7x20x20
=17678.57_ 1257.14=16421.43msquare

Answer 2

given that 
according to the sum π(R²-r²)
from that R =75 , R = 20
= π(R²-r²)
= π(75²-20²)
= 22/7(5625-400)
= 22/7(5255)
= 1159950/7
= 165707.14857.