5.
[tex]a)\\d_1 = 17 \ cm\\d_2 = 14 \ cm\\\\P = \frac{d_1\cdot d_2}{2} = \frac{17 \ cm\cdot14 \ cm}{2} = 17 \ cm\cdot7 \ cm = 119 \ cm^{2}[/tex]
[tex]b)\\a = 5,6 \ cm\\h = 12,3 \ cm\\\\P = a\cdot h = 5,6 \ cm\cdot12,3 \ cm = 68,88 \ cm^{2}[/tex]
[tex]c)\\a = 21 \ cm\\b = 15 \ cm\\h = 4 \ cm\\\\P = \frac{a+b}{2}\cdot h = \fracP21 \ cm + 15 \ cm}{2}\cdot4 \ cm = 36 \ cm\cdot2 \ cm = 72 \ cm^{2}[/tex]
