tolong di bantu kaaa! please

a ) Keliling
= ( 1/2 × 22/7 × 28 ) + ( 22/7 × 14 )
= 44 cm + 44 cm
= 88 cm
b ) Luas yang diarsir
= ( 1/2 × 22/7 × 14 × 14 ) - ( 22/7 × 7 × 7 )
= 308 cm2 - 154 cm2
= 154 cm2