Wzór na pole trapezu
[tex] \frac{(a + b) \times h}{2} [/tex]
Podstawiamy
[tex] \frac{( \frac{1}{2} + \frac{4}{10} ) \times \frac{8}{10} }{2} = \frac{( \frac{5}{10} + \frac{4}{10}) \times \frac{8}{10} }{2} = \frac{ \frac{9}{10} \times \frac{8}{10} }{2} = \frac{ \frac{9}{5} \times \frac{4}{10} }{2} = \frac{ \frac{36}{50} }{2} = \frac{36}{50} \div 2 = \frac{36}{50} \times \frac{1}{2} = \frac{18}{50} \times 1 = \frac{18}{50} = \frac{9}{25} [/tex]
Myślę że pomogłem ;)