# Q.7 Find the perimeter of the rectangle whose length is 40 cm and a diagonal is 41 cm.

Length of rectangle = 40cm
Diagonal = 41 cm
$$Breath^2 = 41^2 - 40^2$$
Or, $$breath^2= 1681 – 1600$$
Or, breath = $$\sqrt{81}$$ cm
Breath = 9 cm
Perimeter of rectangle = 2×(40+9) = 2×49 = 98 cm