1.

Find the area of a triangle.its two sides are 18cm and 10cm, perimeter is 42 cm

Answer» ALIGN="absmiddle" ALT="\sf \bf \huge {\boxed {\MATHBB {QUESTION}}}" class="latex-formula" id="TexFormula1" src="https://tex.z-dn.net/?f=%20%5Csf%20%5Cbf%20%5Chuge%20%7B%5Cboxed%20%7B%5Cmathbb%20%7BQUESTION%7D%7D%7D%20" title="\sf \bf \huge {\boxed {\mathbb {QUESTION}}}">

\tt Find \:the\: area\: of \:a \:triangle.\:Its\: two \:sides \:are\: 18\:cm\\\tt and\: 10\:cm, \:perimeter\: is\: 42\: cm.

\sf \bf \huge {\boxed {\mathbb {ANSWER}}}

\sf \bf {\boxed {\mathbb {GIVEN}}}

  • \bf First \:side\:of\:the \:triangle(a) = 18\:cm
  • \bf Second\:side\:of\:the \:triangle(b) = 10\:cm
  • \bf Perimeter \:the \:triangle(P) = 42\:cm

\sf \bf {\boxed {\mathbb {TO\:FIND}}}

  • \bf Area\:of\:the \:triangle(A)

\sf \bf {\boxed {\mathbb {SOLUTION}}}

{\pink {\underline {\bf {\pmb {Third \:side\:of\:the \:triangle(c)}}}}}

{\blue {\boxed {\boxed {\boxed {\green {\pmb {P_{(Triangle)}=a+b+c}}}}}}}

  • \sf P= perimeter\:of\:the \:triangle
  • \sf a=first \:side \:of\:the \:triangle
  • \sf b=second\:side \:of\:the \:triangle
  • \sf c=third \:side \:of\:the \:triangle

{\underbrace {\overbrace {\orange {\pmb {Substitute \:the \:values}}}}}

\bf \implies 42=18+10+c

\bf \implies 42=28+c

\bf \implies c=42-28

\implies {\blue {\boxed {\boxed {\purple {\sf c=14\:cm}}}}}

————————————————————————————

{\pink {\underline {\bf {\pmb {Semiperimeter \:of\:the \:triangle(S)}}}}}

{\blue {\boxed {\boxed {\boxed {\green {\pmb {S=\dfrac{P}{2}}}}}}}}

  • \sf S=semiperimeter \:of\:the \:triangle
  • \sf P=perimeter \:of\:the \:triangle

{\underbrace {\overbrace {\orange {\pmb {Substitute \:the \:values}}}}}

\bf \implies S=\dfrac{42}{2}

\bf \implies S=\dfrac{\cancel{42}}{\cancel{2}}

\implies {\blue {\boxed {\boxed {\purple {\sf S=21\:cm}}}}}

——————————————————————————————

{\pink {\underline {\bf {\pmb {Area \:of\:the \:triangle(A)}}}}}

{\blue {\boxed {\boxed {\boxed {\green {\pmb {A_{(Triangle)}=\sqrt{S\Big(S-a\Big) \Big(S-b\Big) \Big(S-c\Big)}}}}}}}}

  • \sf A=area\:of \:the \:triangle
  • \sf S=semiperimeter \:of\:the \:triangle
  • \sf a=first \:side \:of\:the \:triangle
  • \sf b=second\:side \:of\:the \:triangle
  • \sf c=third \:side \:of\:the \:triangle

{\underbrace {\overbrace {\orange {\pmb {Substitute \:the \:values}}}}}

\bf \implies A=\sqrt{21\Big(21-18\Big) \Big(21-10\Big) \Big(21-14\Big)}

\bf \implies A=\sqrt{21\Big(3\Big) \Big(11\Big) \Big(7\Big)}

\bf \implies A=\sqrt{21\times 3\times 11\times 7}

\bf \implies A=\sqrt{4851}

\bf \implies A=\sqrt{441\times 11}

{\blue {\boxed {\boxed {\purple {\mathfrak {A=21\sqrt{11}\:{cm}^{2}}}}}}}

{\underbrace {\red {\overline {\red {\underline {\red {\pmb {\sf {{\therefore} The\:area \:of \:the \:triangle \:is\:21\sqrt{11}\:{cm}^{2}}}}}}}}}}

\sf \bf \huge {\boxed {\mathbb {HOPE \:IT \:HELPS \:YOU}}}

____________________________________________

\sf \bf \huge {\boxed {\mathbb {EXTRA\:INFORMATION}}}

\sf Area \:of \:the \:triangle = \dfrac{1}{2}bh

\sf Perimeter\:of \:the \:triangle =a+b+c



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