Răspunsuri

2014-05-01T17:08:02+03:00
Construiesti inaltimea trapezului si o notezi CM
In ΔCMB, mM=90, mB=45⇒m BCM=45⇒ΔCMB dreptunghic isoscel
DC=12
DC//AM, DC≡AM⇒AM=12
MB=20-12=8
in ΔCMB, aplici Pitagora ⇒CB=8√2
P=DC+DA+AB+CB
P=12+8+20+8√2=40+8√2=8(5+√2)
A=(DC+AB)*CM/2
A=(20+12)*8/2=128