Question

What is the length of the third side of a triangle if one side measures 10cm the second measures 15cm and the perimeter is 45cm​

Answer 1

Answer:

perimeter = 45 cm

sides = 10 cm, 15 cm, x cm

p = s + s + s

45 = 10 + 15 + x

x = 45 - (10 + 15)

x = 45 - 25

x = 20 cm

third side = 20 cm

Answer 2

Given : Perimeter of a triangle is 45 cm and two of its sides are 10 cm and 15 cm .

To Find :

• Find the 3rd Side

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SolutioN :

$\maltese$ Formula Used :

• ${\underline{\boxed{\pmb{\sf{ Perimeter {\small_{(Triangle)}} = Side_1 + Side_2 + Side_3 }}}}}$

$\maltese$ Calculating the 3rd Side :

$\begin{gathered} \qquad \; \longrightarrow \; \; \sf { Perimeter = Side_1 + Side_2 + Side_3 } \\ \\ \\ \end{gathered}$

$\begin{gathered} \qquad \; \longrightarrow \; \; \sf { 45 = 10 + 15 + Side_3 } \\ \\ \\ \end{gathered}$

$\begin{gathered} \qquad \; \longrightarrow \; \; \sf { 45 = 25 + Side_3 } \\ \\ \\ \end{gathered}$

$\begin{gathered} \qquad \; \longrightarrow \; \; \sf { 45 - 25 = Side_3 } \\ \\ \\ \end{gathered}$

$\begin{gathered} \qquad \; \longrightarrow \; \; {\underline{\boxed{\pmb{\sf{ Side \; 3 = 20 \; cm }}}}} \; {\red{\pmb{\bigstar}}} \\ \\ \\ \end{gathered}$

$\therefore \;$ 3rd Side of the Triangle is 20 cm .

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