garis dan sudut

JAWAB:
 $\angle A=\frac{1}{5}\times180\degree=36\degree$  

 $\angle A=60\degree$    $Misal\ sudut\ itu=\angle A$  
 $Pelurus\ \angle A=4\ penyiku\ \angle A$  
 $180\degree-\angle A=4\left(90\degree-\angle A\right)$  
 $180\degree-\angle A=360\degree-4\angle A$  
 $-\angle A+4\angle A=360\degree-180\degree$  
 $3\angle A=180\degree$