Question

The ratio between the length and breadth of a rectangular field is 5: 4. If the breadth is 20
metres less than the length, the perimeter of the field is
(a) 260 m
(b) 280 m
(c) 360 m
(d) None of these​

Answer 1

Sᴏʟᴜᴛɪᴏɴ :-

Let us Assume That, length and breadth of a rectangular field are 5x & 4x.

So,

→ Length - Breadth = 20m

→ 5x - 4x = 20

→ x = 20m.

Therefore,

→ Length of Rectangle = 5x = 5*20 = 100m.

→ Breadth of Rectangle = 4x = 4*20 = 80m.

Hence,

→ Perimeter of Rectangular Field = 2(Length + Breadth) = 2(100 + 80) = 2 * 180 = 360m. (C) (Ans.)

______________________

Extra :-

1) Each of the interior angles of a rectangle is 90°.

2) The diagonals of a rectangle bisect each other.

3) The opposite sides of a rectangle are parallel.

4) The opposite sides of a rectangle are equal.

5) A rectangle whose side lengths are a and b has area = a×b×sin90° = a×b

6) A rectangle whose side lengths are a a and b b has perimeter 2(a + b)...

7) The length of each diagonal of a rectangle whose side lengths are a and b is √(a²+b²)..

_____________________

Answer 2

Answer:

• Ratio of Length & Breadth = 5 : 4
• Breadth is 20 m less than Length.

✩ LENGTH⠀⠀⠀⠀ ⠀ :⠀⠀⠀⠀ ⠀ BREADTH

⠀⠀⠀⠀5⠀⠀⠀⠀⠀ ⠀ ⠀ :⠀⠀⠀⠀⠀ ⠀ ⠀4

Difference between Ratio is (5 - 4) = 1

We will Divide The Real Difference of Dimension i.e. 20 by 1, After that We will Multiplying this by Each of Ratio.

⇴ (Diff. of Ratio × Difference)

⇴ (1 × 20)

⇴ 20 ⠀⠀[ Number to Multiply Ratios ]

⠀⠀⠀⠀ ⠀ ⠀______________________

✩ LENGTH⠀⠀⠀⠀ ⠀ :⠀⠀⠀⠀ ⠀ BREADTH

⠀⠀⠀⠀5⠀⠀⠀⠀⠀ ⠀ ⠀ :⠀⠀⠀⠀⠀ ⠀ ⠀4

⠀⠀⠀× 20 m⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⠀ ⠀ × 20 m

⠀⠀⠀100 m⠀⠀⠀⠀⠀ ⠀⠀⠀⠀ ⠀ ⠀⠀80 m

━━━━━━━━━━━━━━━━━━━━━━━━

☢ According to the Question Now :

⇢ Perimeter = 2(Length + Breadth)

⇢ Perimeter = 2(100 m + 80 m)

⇢ Perimeter = 2 × 180 m

⇢ Perimeter = 360 m

⠀

∴ Perimeter of rectangular field is c) 360 m.