a)
[tex] \frac{a \times h}{2} = \frac{5 \times 4}{2} = \frac{20}{2} = 10[/tex]
b)
[tex]a \times h = 6 \times 8 = 48[/tex]
c)
[tex] \frac{(a + b) \times h}{2} = \frac{(12 + 5) \times 5}{2} = \frac{17 \times 5}{2} = \frac{85}{2} = 42.5[/tex]
