Question Number 132900 by aurpeyz last updated on 17/Feb/21
$${a}\:{pinhole}\:{camera}\:{is}\:{placed}\:\mathrm{300}{cm} \\ $$$${in}\:{front}\:{of}\:{a}\:{building}\:{so}\:{that}\:{the}\:{image} \\ $$$${is}\:{formed}\:{on}\:{a}\:{screen}\:\mathrm{5}{cm}\:{from}\:{the} \\ $$$${pin}\:{hole}.\:{if}\:{the}\:{image}\:{is}\:\mathrm{2}.\mathrm{5}{cm}\:{high}. \\ $$$${the}\:{height}\:{of}\:{the}\:{building}\:{will}\:{be}? \\ $$
Commented by mr W last updated on 17/Feb/21
$${supposed}\:{you}\:{don}'{t}\:{mean}\:{a}\:{real} \\ $$$${building}\:{for}\:{human},\:{but}\:{a}\:{dog}\:{house}.\: \\ $$$$\frac{{x}}{\mathrm{300}}=\frac{\mathrm{2}.\mathrm{5}}{\mathrm{5}} \\ $$$$\Rightarrow{x}=\mathrm{150}\:{cm} \\ $$$${the}\:{height}\:{of}\:{dog}\:{house}\:{is}\:\mathrm{150}{cm}. \\ $$