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https://vle.mathswatch.co.uk/images/questions/question812.png

jakeharris02  Nov 4, 2017

Best Answer 

 #2
avatar+92430 
+1

If we extended the top base of the figure by 8m and drew a perpendicular line to the base...the additional area would create a right "Pythagorean Triple" triangle with one of the legs  = 8m and a hypotenuse of 17m.....and the other leg = sqrt (17^2 - 8^2)  = sqrt (225) =  15m  = the length of the fence

 

Thus....disregarding the right triangle, we have a trapezoid with a height of 15m and two bases of 12m and 20m

 

So....the  area of a trapezoid  =

 

(height) / 2  *  (sum of the bases )   =

 

15 / 2  * ( 12 + 20)  =

 

7.5 *  32   =

 

240 m^2

 

So...we need three cans of weedkiller  =  3 * 19.75  =  59.25 pounds  (total cost) 

 

 

cool cool cool

CPhill  Nov 4, 2017
 #1
avatar+544 
-1

(AREA OF LAWN) 256 sqare meters

 

19.75*2 = 39.5

 

19.75/2 = 9.87500

 

9.87500 + 39.5 = 49.37500

 

(UNIT PRICE) 0.9875

 

0.9875 * 9 = 8.8875

 

9.87500 + 39.5 = 49.37500 + 8.8875 = 58.2625 ≈ 58.26

 

 

≈ $58.26

 

laughlaughlaugh

ProMagma  Nov 4, 2017
edited by ProMagma  Nov 4, 2017
 #2
avatar+92430 
+1
Best Answer

If we extended the top base of the figure by 8m and drew a perpendicular line to the base...the additional area would create a right "Pythagorean Triple" triangle with one of the legs  = 8m and a hypotenuse of 17m.....and the other leg = sqrt (17^2 - 8^2)  = sqrt (225) =  15m  = the length of the fence

 

Thus....disregarding the right triangle, we have a trapezoid with a height of 15m and two bases of 12m and 20m

 

So....the  area of a trapezoid  =

 

(height) / 2  *  (sum of the bases )   =

 

15 / 2  * ( 12 + 20)  =

 

7.5 *  32   =

 

240 m^2

 

So...we need three cans of weedkiller  =  3 * 19.75  =  59.25 pounds  (total cost) 

 

 

cool cool cool

CPhill  Nov 4, 2017
 #3
avatar+544 
-1

Dang.. I was close

ProMagma  Nov 4, 2017

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