a)

Dane:

$h=1,5dm$

$a+b=2h=2\cdot 1,5dm=3dm$

Pole Trapezu

$P=\frac{1}{2}\left(a+b\right)\cdot h=\frac{1}{2}\cdot 3dm\cdot 1,5dm=\frac{3}{2}dm\cdot \frac{3}{2}dm=\frac{9}{4}d{m}^2=$ $2\frac{1}{4}d{m}^2$

 b)

Dane:

a + b + c = 24 cm

h = a + 2 cm

h = b + 4 cm

Wysokość trapezu

h = a + 2 cm

h - 2 cm = a

a + b + h  = 24 cm

h - 2 cm + h - 4 cm +h = 24 cm

3h  - 6 cm = 24 cm

3h = 30 cm

h = 10 cm

Długości podstaw trapezu

a = h - 2 cm = 10 - 2 = 8 cm

b = h - 4 cm = 10 - 4 cm = 6 cm

Pole trapezu

$P=\frac{1}{2}\left(a+b\right)\cdot h=\frac{1}{2}\cdot \left(8cm+6cm\right)\cdot 10cm=\frac{1}{2}\cdot 10\cdot 14cm=$ $5cm\cdot 14cm=70c{m}^2$