Question

Calendario matemático marzo 2020 nivel 2 pregunta 1

Answer 1

 The perimeter and area  trapezium ABCE  are :   P ABCE = 140 cm ;   A ABCE = 1000 cm².

P ABCD = 160 cm

P ABCD = 4L = 160   ⇒  L = 160 /4 = 40 cm   the  side of square  

 Pythagoras theorem :

      AE² = AD²+ DE²       clears  DE :

      DE = √( AE²- AD² )

      DE = √( 50 cm )²- ( 40 cm )²

      DE = 30 cm

    the side is : CE = 40 cm -30 cm = 10 cm

  The perimeter of trapezium ABCE is:

        P ABCE = AB +BC +CE +AE

        P ABCE = 40 cm +40 cm +50 cm +10cm

        P ABCE = 140 cm

  The area  trapezium ABCE is :

          A ABCE = ( AB +EC )*BC/2 = ( 40cm +10 cm ) *40 cm /2

         A ABCE = 1000 cm²