Odpowiedź:
[tex]3. \: a = 5cm \\ h = a + 3cm = 5cm + 3cm = 8cm \\ P = \frac{ah}{2} = \frac{5 \times 8}{2} = \frac{40}{2} = {20cm}^{2} [/tex]
[tex]4. \: a = 4cm \\ h = 2a = 2 \times 4cm = 8cm \\ P = \frac{ah}{2} = \frac{4 \times 8}{2} = \frac{32}{2} = {16cm}^{2} [/tex]
[tex]5. \: h = 24cm \\ a = \frac{h}{3} = \frac{24}{3} = 8cm \\ P = \frac{ah}{2} = \frac{8 \times 24}{2} = \frac{192}{2} = {96cm}^{2} [/tex]
[tex]6. \: a = 8cm \\ h = 8cm \\ P = \frac{ah}{2} = \frac{8 \times 8}{2} = \frac{64}{2} = {32cm}^{2} [/tex]
[tex]7. \: a = 2h \\ 2h + h = 18 \\ 3h = 18 \\ h = 18 \div 3 \\ h = 6cm \\ a = 2h = 2 \times 6 = 12cm \\ P = \frac{ah}{2} = \frac{12 \times 6}{2} = \frac{72}{2} = 36 {cm}^{2} [/tex]
