Question

the surface area of the cuboid is 1372 sq.cm. if its dimensions are in the ratio of 4:2: 1 then find its lenght

Answer 1

Answer:

Length= 4a

Breadth= 2a

Height=1a

Area of cuboid=1372sq.cm.

Total Area of Cuboid= 2(lb+bh+hl)

2(4a×2a+2a×a+a×4a)=1372sq.cm.

8a2+2a2+4a2=1372÷2

14a2=686sq.cm.

a2=686÷14

a2= 49sq.cm.

a=7cm.

length=4a

4×7cm.

28cm.

Answer 2

Hey Mate.......... Here You Go..........

Answer:

Length = 4x = 4(7) = 28cm

Breath = 2x =2(7) = 14cm

Height = x = 7cm

Step-by-step explanation:

Length - 4x

Breath - 2x

Height - x

Total Surface Area of a Cuboid = 2 [ lb + bh + hl ]

                                           1372 = 2 [ ($4x$)($2x$) + ($2x$)($x$) + ($x$)($4x$) ]

                                           1372 = 2 [ $8x^{2}$ + $2x^{2}$ + $4x^{2}$ ]

                                           1372 = 2 [ $14x^{2}$ ]

                                            686 = $14x^{2}$

                                              49 = $x^{2}$

                                            $\sqrt{49}$ = $x$

                                                 7 = $x$

Length = 4x = 4(7) = 28cm

Breath = 2x =2(7) = 14cm

Height = x = 7cm

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