Question

Find the perimeter of the rectangle whose length is 40cm and a diagonal is 41cm.​

Answer 1

Answer:

Consider diagonal and the included length and angle is 90°

Let breadth be x

It is right angle triangle

41^2 = 40^2 + x^2

x^2=41^2 -40^9

= 81

x= root 81=9

Breadth is 9

Perimeter of rectangle =2 (l+b)

= 2(40+9)

=2×49

=98

Answer 2

Answer:

98cm

Step-by-step explanation:

As you see in rectangle ABCD, the diagonal is 41 cm and the length is 40cm. The diagonal forms two triangles. According to Pythagoras Theorem,

AC² = AB² + BC²

41² = 40² + BC²

1681 = 1600 + BC²

1681 - 1600 = BC²

81 = BC²

√81 = BC

9 = BC

Here, we got the breadth.

Breadth = 9cm

P = 2(L+B)

P = 2(40 + 9)

P = 2 × 49

P = 98cm