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Find the Area of a Triangle Whose Sides Are 18 Cm, 24 Cm and 30 Cm Also, Find the Length of Altitude Corresponding to the Largest Side of the Triangle - Mathematics

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Question

Find the area of a triangle whose sides are 18 cm, 24 cm, and 30 cm. Also, find the length of altitude corresponding to the largest side of the triangle.

Sum

Solution

Since the sides of the triangle are 18 cm, 24 cm and 30 cm respectively.

s = `(18 + 24 + 30)/(2)`
  = 36

Hence the area of the triangle is 

A  = `sqrt (s( s - a ) ( s - b ) (s -c ))`

    = `sqrt (36( 36 - 18 ) ( 36 - 24 ) (36 -30 ))`

    = `sqrt (36 xx 18 xx 12 xx 6 )`

    = ` sqrt ( 46656 ) `

    = 216 sq.cm.

Again

A = `1/2 "base" xx "altitude" `

Hence

216 = `1/2 xx 30 xx h`
h = 14.4cm

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Chapter 20: Area and Perimeter of Plane Figures - Exercise 20 (A) [Page 247]

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Selina Concise Mathematics [English] Class 9 ICSE
Chapter 20 Area and Perimeter of Plane Figures
Exercise 20 (A) | Q 1 | Page 247
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