Question

find the perimeter of rectangle whose length is 20 cm and diagonal is 21 CM
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Answer 1

Answer:

52.81

Step-by-step explanation:

(l=length)

Using the formulas

P=2(l+w)

d=w2+l2

Solving forP

P=2l+2√d2﹣l2

=2·20+2·212﹣202

=52.806

Answer 2

Answer: length= 20 cm

and diagonal= 21 cm

and we know all angles of a rectangle are 90 degree

now length , breadth and diagonal form a right angled triangle

therefore,$20^{2} +b^{2} =21^{2}$

400+$b^{2}$=441

$b^{2}$=41 and b=$\sqrt{41}$

perimeter = 2(a+b)

=2(20+$\sqrt{41}$)

=40+2$\sqrt{41}$

for better understanding see image

hope it helps u and  if so mark me as brainliest!!!!