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avatar+121 

 

If the area of rABC is 20 cm2, what is the area of rPQR? 

If you can please show how you got your answer, I'm a bit confused on this question. 

AgentFatboy  Apr 10, 2018
 #1
avatar+92367 
+2

The scale factor  from   ABC  to RQR  is      6/4  =  3/2  =  1.5

 

So....each dimension  of  PQR  is 1.5 times that of ABC

 

Now....just for the heck of it,if we let the base of ABC  = 4 cm...so.... its altitude must be 10 cm

 

Proof  ..area ABC  =   (1/2) base * altitude  =  (1/2) (4) (10)  =  20  cm^2

 

So....since each dimension of PQR  is 1.5 times that of ABC, its altitude must be 10 * 1.5  = 15 cm

And let its base  = 6cm

 

So...it's area is just  (1/2) (6) ( 15)  =  45 cm^2

 

Note that  we could obtain the same result  by taking the area of ABC  and multiplyng this by the square of the scale factor

 

Proof :   20 (1.5)^2   =  20 (3/2)^2  =  20 * 9 / 4  =  180  / 4   = 45  cm^2

 

Hope that helps  !!!

 

 

cool cool cool

CPhill  Apr 10, 2018
 #2
avatar+121 
+1

yup that helps, thank ya 

AgentFatboy  Apr 10, 2018

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