a)
[tex]P = a \times b[/tex]
[tex]a = 3.5dm[/tex]
[tex]b = 0.3dm[/tex]
[tex]P = 0.3dm \times 3.5dm = 1.05 {dm}^{2} [/tex]
b)
[tex]P = \frac{1}{2} \times (a + b) \times h[/tex]
[tex]a = 8cm[/tex]
[tex]b = 5cm[/tex]
[tex]h = 3cm[/tex]
[tex]P = \frac{1}{2} \times (8cm + 5cm) \times 3cm[/tex]
[tex]P = 8 {cm}^{2} [/tex]
c)
[tex]P = \frac{1}{2} \times a \times h[/tex]
[tex]a = 6cm[/tex]
[tex]h = 8cm[/tex]
[tex]P = \frac{1}{2} \times 6cm \times 8cm = 24 {cm}^{2} [/tex]
