Question

9.Find the perimeter of the rectangle whose length is 40 cm and a diagonal is 50cm

Answer 1

Answer:

Length=40cm.

Diagonal=50cm.

Perimeter of rectangle =?.

Perimeter of rectangle=2(l+d).

=2(40+50).

=2(90).

=180cm.

I think this is your answer.

Answer 2

Answer:

In ∆ACD

AB=CD=40cm

AD=50cm

/_ACD=90°(rectangle has 90° on all the both sides)

By Pythagoras method

(AD) sq. =(AC)sq.+(CD)sq.

(AD)sq.- (CD) sq.=(AC)sq.

(50)sq -(40)sq.=(AC)sq.

2500-1600=(AC)sq.

900=(AC) sq.

AC=✓900

AC=30

Perimeter of rectangle ABCD=2(l+b)

=2(40+30)

=2(70)=

=140 cm