Question

a sport ground has radius 30 metre the middle ground for playing is 10 metre in radius ,find the area left for sitting audience

Answer 1

$(\pi \times {30}^{2}) - (\pi \times {10}^{2} )$
this is the area for sitting the audience

Answer 2

the area left for people to sit = Area of field -area of the playground(take pie as 3.14)
                                                 = (3.14×(30²)) - (3.14×(10²)) (take out the brackets and then both the pie will cancel out)
                                                 = (30²) - (10²
                                                 = (900) - (100)
                                                 = 800m² (area left for audience)