a)
[tex]P = \frac{e \times f}{2} \\ \\ P = \frac{15cm \times \not12_ \bold{6}cm}{ \not2_ \bold{1}} = 90 {cm}^{2} [/tex]
b)
[tex]P = \frac{(a + b) \times h}{2} \\ \\ P = \frac{(14cm + 7cm) \times \not6_ \bold{3}cm}{ \not 2_ \bold{1}} = 21cm \times 3cm = 63 {cm}^{2} [/tex]
c)
[tex]P = \frac{a \times h}{2} \\ \\ P = \frac{ \not24_ \bold{12}cm \times 5cm}{ \not2_ \bold{1} } = 60 {cm}^{2} [/tex]
