Question

Perimeter of an isosceles triangle is 40cm. Its equal side is 4cm less than the third side. Use l as the length of the third side. Answer fast!

Answer 1

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▪ Perimeter of an Isosceles triangle is 40 cm. its equal side is 4 cm less than the third side.
Find the sides of the triangle.

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${ \orange{ \underline{ \bold{Given-}}}}$

▪ Perimeter of the Isosceles triangle = 40 cm

let the third side of the triangle be l cm

${ \bold{ according \: to \: the \: question}}$

the two equal sides are 4 cm less than the third side

then ,

▪ the length of the 2 sides are (l-4) cm..

${ \boxed{ \red{ \bold{ \: Perimeter = sum \: of \: all \: sides \: }}}}$

the sides of this Isosceles triangle are-

• (l-4) cm

• (l-4) cm

• l cm

${ \orange{ \bold{40 cm = l cm + (l- 4)cm + (l- 4)cm}}}$

${ \bold{ \implies{40 = 3l- 8}}}$

${ \bold{ \implies{3l = 40 + 8}}}$

${ \bold{ \implies{3l= 48}}}$

${ \boxed{ \bold{ \red{ \: \: l= 16 \: cm \: \: }}}}$

therefore,

the length of the third side = l cm = 16 cm

and the length of other two equal sides are (l-4) cm = ( 16-4)cm = 12 cm

${ \boxed{ \bold{ \red{the \: sides \: are \: 12cm \: , \: 12 \: cm \: and \: 16cm}}}}$