Monday, December 21, 2015

What is wrong with this circle's area problem?



My solution and my book's solution don't match.



Is something wrong with the my solution?
If so, where and why?



My book says:





The radius r of a circle increases by 50%.
In terms of r, what is the area of the circle
with the increased radius?




My solution:




  1. A = πr2  => Area of any circle

  2. ir =  3r/2  => Increased radio

  3. A ir=πir2  => Area of circle with increased radio

  4. A ir=π(3r/2)2  => Substituting ir with its value


  5. A ir=π(9r2/4)  => Square

  6. A ir= (9πr2)/4  => Result



Is the In terms of r tricky?


Answer



There is nothing wrong with your answer!


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