Question

Simplify: -1-2-3 - .... (-20 )​

Answer 1

Step-by-step explanation:

⟹letthelengthofsidesbe=x

:⟹itsperimeter=180cm

:⟹3x+4x+5x=180

:⟹12x=180

:⟹x=

12

180

=15cm

\begin{gathered}\sf : \implies \: 3x = 3 \times 15 = 45 \\ \\ \sf : \implies \: 4x = 4 \times 15 = 60 \\ \\ \sf : \implies \: 5x = 5 \times 15 = 75 \\ \\ \sf : \implies \: s \: = \frac{a + b + c}{2} \\ \\ \sf : \implies \: s \: = \frac{45 + 60 + 75}{2} = \frac{180}{2} = 90\end{gathered}

:⟹3x=3×15=45

:⟹4x=4×15=60

:⟹5x=5×15=75

:⟹s=

2

a+b+c

:⟹s=

2

45+60+75

=

2

180

=90

\begin{gathered}\sf : \implies \: by \: using \: herons \: formula \\ \\ \sf : \implies \: \sqrt{s(s - a)(s - b)(s - c)} \\ \\ \sf : \implies \: \sqrt{90(90 - 45)(90 - 60)(90 - 75)} \\ \\ \sf : \implies \: \sqrt{90(45)(30)(15)} \\ \\ \sf : \implies \: \sqrt{1822500} \\ \\ \sf : \implies \: 1350 \: cm {}^{2}\end{gathered}

:⟹byusingheronsformula

:⟹

s(s−a)(s−b)(s−c)

:⟹

90(90−45)(90−60)(90−75)

:⟹

90(45)(30)(15)

:⟹

1822500

:⟹1350cm

2