Problema Solution

FIND THE DIMENSIONS OF A RECTANGLE WHOSE PERIMETER IS 46 METERS AND WHOSE AREA IS 126 METERS squared

Answer provided by our tutors

Perimeter of a rectangle = 2 ( length + breadth )



46 = 2 ( length + breadth )



That is, Length + breadth = 46/2




Length + breadth = 23




length = 23 - breadth


let Length= L and Breadth =B

=> L = 23 - B                                -----(1)



Area is given as 126 meters



Tat is,



L * B = 126                                      -----(2)




Now substitute the value, L= 23 - B in the second equation,



===> ( 23 - B ) * B = 126



Remove the brackets, by multiplying term by term,



===>23 * B - B * B = 126




==> 23B - B^2 = 126



By arranging the terms, we have a quadratic equation here,



====> -B^2 + 23B = 126


Subteract 126 from both sides of the equation,



===> -B^2 + 23B -126 = 126 -126



===> -B^2 + 23B -126 = 0



This is a quadratic equation ( in variable B )


Using quadratic formula, find solutions ( All possible values of B) of the

equation.

Compare the given equation with the standard equation, ax^2 + bx + c = 0.



Then we have,




 

a = -1 b = 23 and c = -126




We have the quadratic formula,








Here we use the same formula, but for the variable B,








Substitute the values, a, b and c




===>




===>




===>




===> B = (-23 + 5 )/-2 or B = (-23 - 5 )/-2




===> B = (-18 )/-2 or B = (-28 )/-2



===> B = 9 or B = 14



Now, Find out correspopnding values of L



When B = 9,


we have L = 23 - 9 = 14



When B = 14, L = 23 - 14 = 9




So we have two pairs of values,

(Here breadth means width)


Length = 14, breadth = 9


Length = 9 and breadth = 14