[tex]a) P = \frac{(a+ b) * h}{h} \\a = 5cm\\b = 12cm\\h = 3cm\\P = \frac{(12cm + 5cm) * 3cm}{3cm} = \frac{17cm * 3cm}{3cm} = 17cm^2\\b) P = a * h\\a = 6cm\\h = 4cm\\P = 6cm * 4cm = 24cm^2\\c) P = \frac{a * h}{2}\\a = 2cm\\h = 5cm\\P = \frac{2cm*5cm}{2}\\P = 5cm^2\\P = \frac{a*h}{2}\\a = 5cm\\h = 7cm\\P = \frac{5cm*7cm}{2} = \frac{40cm}{2} = 20cm^2\\20cm^2 + 5cm^2 = 25cm^2\\[/tex]
