Romba laukums ir vienāds ar tā malas un augstuma, kurš novilkts pret taisni, kas satur šo malu, garumu reizinājumu: $$S = ah$$
Rombam visas malas ir vienāda garuma, tāpēc jebkuri romba augstumi arī ir vienāda garuma.
Romba laukums ir vienāds ar tā diagonāļu garumu reizinājuma pusi:
$S\left(\mathit{rombam}\right)=\frac{{d}_{1}\cdot {d}_{2}}{2}$
Zīmējumā $$S(ABCD) =$$$\frac{\mathit{AC}\cdot \mathit{BD}}{2}$
Piemērs:
Romba viena diagonāle ir $$12$$$$cm$$. Tā laukums ir $24\phantom{\rule{0.147em}{0ex}}{\mathit{cm}}^{2}$.
Aprēķini otras diagonāles garumu!

Dots: ${d}_{1}=12\phantom{\rule{0.147em}{0ex}}\mathit{cm},\phantom{\rule{0.147em}{0ex}}S=24{\phantom{\rule{0.147em}{0ex}}\mathit{cm}}^{2}$

Jāaprēķina: ${d}_{2}$

Risinājums:
$\begin{array}{l}S=\frac{{d}_{1\cdot }{d}_{2}}{2}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\frac{12\cdot {d}_{2}}{2}=24\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\\ \phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}6\cdot {d}_{2}=24\\ \phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}{d}_{2}=4\phantom{\rule{0.147em}{0ex}}\mathit{cm}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\phantom{\rule{0.147em}{0ex}}\end{array}$

Atbilde: Otras diagonāles garums ir $$4$$$$cm$$.
Atsauce:
Matemātika 8.klasei / Ilze France, Gunta Lāce, Ligita Pickaine, Anita Miķelsone. -Rīga : Lielvārds, 2008. – 272 lpp. :il. – izmantotā literatūra: 245.-246.lpp.