=8x9
=72(cm? )
a = s \h
=72÷7.2
= 10 (cm)
So the bottom is 10cm.
2、
s=ah÷2
=5×3÷2
=7.5(cm? )
=3×3÷2
=4.5(cm? )
4.5+7.5= 12cm?
The area is 12cm? .