Question

what will be the perimeter ?????​

Answer 1

Answer:

The perimeter of a rectangle is the total length of all the sides of the rectangle. Hence, we can find the perimeter by adding all four sides of a rectangle. Perimeter of the given rectangle is a + b + a + b.

Step-by-step explanation:

Answer 2

$using \: the \: sine \: law \\ \\ \frac{sine \: a}{n - 1} = \frac{sine \: 2a}{n \: + 1} \\ \\ 2cos \: a = \frac{n + 1}{(n - 1)} \\ \\ cos \: a \: = \frac{n + 1}{2(n - 1)} \\ \\ . \frac{ {n}^{2} + (n + {} 1 {)}^{2} - (n - {1)}^{2} }{2n(n + 1) } \\ \\ = \frac{(n - 1)}{2(n - 1)} (using \: cosine \: law) \\ \\ . \frac{ {n}^{2} + 4n}{2n + (n + 1)} = \frac{(n + 1)}{2(n - 1)} \\ \\ . \frac{n + 4}{2(n + 1)} = \frac{n + 1}{2(n - 1)} \\ \\ . \: (n + {1)}^{2} = (n + 4) \: (n - 1) \\ \\ = n \: = 5 \\ hence \: the \: length \: of \: the \: side \: of \\ the \: triangle \: is \: 4 ,\: 5 ,\: 6 \\ \\ \\ now \: we \: can \: find \: the \: perimeter \: \\ easily \: . \\ perimeter \: of \: the \: triangle \: is \: \\ 4 + 5 + 6 = 15 \\ perimeter \: = 15$

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