tolong pake caranya iyakk plisss

12. luas juring =90/360×π×r²
=¼×3,14×10²
=¼×3,14×100
=¼×314
=78,5
luas segitiga=a×t/2
=10×10/2
=100/2
=50
luas arsiran=78,5-50
=28,5