Question 156530
W=2L-6
L(2L-6)=180
2L^2-6L-180=0
2(L^2-3L-90)=0
{{{L = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}} 
L=(3+-SQRT[-3^2-4*1*-90])/2*1
L=(3+-SQRT9+360])/2
L=(3+-SQRT369)/2
L=(3+-19.21)/2
L=(3+19.21)/2
L=22.21/2
L=11.1 cm. IS THE LENGTH.
W=2*11.1-6
W=22.2-6
W=16.2 cm. IS THE WIDTH.
C^2=11.1^2+16.2^2
C^2=123.21+262.44
C^2=385.65
C=SQRT385.65
C=19.64 cm. LENGTH OF THE DIAGONAL.