tolong bantu nomer 4 dan 5.

4.
Busur AB= sudut/360 *2*π*r
Busur AB= 72/360 *2*3,14*20= 25,12 cm

5.
sudut1 : sudut2 : sudut3=3:5:10
total= 3+5+10= 18

sudut1= 3/18 *360= 360/6= 60°
sudut2= 5/18 *360= 5*20= 100°
sudut3= 10/18 *360= 10*20= 200°