SOLUTION: Find the value of x, correct to 1 decimal place, in this diagram if the area is to be 20 square units. Diagram: http://imgur.com/a/d2Kdt Here is my working, the answer I got

Algebra ->  Surface-area -> SOLUTION: Find the value of x, correct to 1 decimal place, in this diagram if the area is to be 20 square units. Diagram: http://imgur.com/a/d2Kdt Here is my working, the answer I got       Log On


   

Question 1055210: Find the value of x, correct to 1 decimal place, in this diagram if the area is to be 20 square units.
Diagram: http://imgur.com/a/d2Kdt
Here is my working, the answer I got is different from the answer in the book which is 1.6
x(x+10)+ 1/2(pi x^2) =20
x^2 +10x + 1/2(pi x^2)= 20
2x^2+20x+pi x^2=40
(2+pi)x^2+20x-40=0
since x>0, x=1.455
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
First step is wrong.
Idea of sum of the two area parts is conceptually correct.

highlight_green%28x%28x%2B10%29%2B%28pi%2F2%29%28x%2F2%29%5E2=20%29
NOW you should be able to solve and find a better result.