7. Find the perimeter of the rectangle whose length is 40 cm and a diagonal is 41 cm.
As we can see in the rectangle,
By Pythagoras theorem,
Now as given in the question,
Diagonal = 41 cm.
Length = 40 cm.
So, Putting these value we get,
Hence the width of the rectangle is 9 cm.
So
The perimeter of the rectangle = 2 ( Length + Width )
= 2 ( 40 cm + 9 cm )
= 2 x 49 cm
= 98 cm
Hence the perimeter of the rectangle is 98 cm.