Tolong dijawab ya No 1 a-d pake rumus dan caranya

1. 18×10÷2=90
1. 25×15÷2=187,5
3. 7×5÷2=16,5
4. 8×12÷2= 24
5. 30×14÷2= 210

A.L=1/2×a×t
=1/2×18×10
=1/2×180
=90cm2
b.L=1/2×a×t
=1/2×25×15
=1/2×375
=187,5cm2
c .L=1/2×a×t
=1/2×7×5
=1/2×35
=17,5cm2
d .L=1/2×a×t
=1/2×8×12
=1/2×96
=48cm2