+0  
 
0
216
2
avatar

A rectangle is divided into four small rectangles as shown. The areas of three of the four small rectangles are labeled in the diagram. What is the area of the remaining small rectangle?

pls solve quickly! Thanks ;)

off-topic
Guest Oct 3, 2017
edited by Guest  Oct 3, 2017
edited by Guest  Oct 3, 2017
edited by Guest  Oct 3, 2017
edited by Guest  Oct 3, 2017
Sort: 

2+0 Answers

 #1
avatar+7056 
+2

 

ab  =  4     →     a  =  4 / b

bd  =  3

cd  =  5     →     c  = 5 / d

 

area of remaining rectangle  =  ac  =  \(\frac4b\cdot\frac5d=\frac{20}{bd}=\frac{20}{3}\)

hectictar  Oct 3, 2017
 #2
avatar+86649 
+2

Thanks, hectitctar!!!......there is a sligtly faster way of finding the missing area

 

Using hectictar's diagram [ along with a theorem from Euclid ]

 

        area of ab *  area of dc =   area of bd * area of ac

 

               4        *         5            =         3        *    area of ac

 

                      20                      =          3        *    area of ac      

 

                                Divide both sides by 3

 

 

                                20 / 3   =  area of ac   

 

 

 

cool cool cool  

CPhill  Oct 4, 2017
edited by CPhill  Oct 4, 2017

11 Online Users

New Privacy Policy (May 2018)

We use cookies to personalise content and advertisements and to analyse access to our website. Furthermore, our partners for online advertising receive pseudonymised information about your use of our website. Please click on "Accept cookies" if you agree to the setting of cookies. Cookies that do not require consent remain unaffected by this, see cookie policy and privacy policy.