Question

(( need the best answers from mods and stars ))

।Do not copy or spam।

In the given figure, from a cuboidal solid metallic block, of dimensions 15 cm x 10 cm x 5 cm, a cylindrical hole of diameter 7 cm is drilled out. Find the surface area of the remaining block.

$\sf {\left[Use \:\pi=\dfrac{22}{7}\right]}$​

Answer 1

Step-by-step explanation:

Given :-

Measurements of a cuboid are 15 cm, 10 cm and 5cm

A cylindrical hole of diameter 7cm is drilled out from that .

To find:-

Find the surface area of the remaining block.

Solution:-

Length of the cuboid = 15 cm

Breadth of the cuboid = 10 cm

Height of the cuboid = 5 cm

Total surface area of a cuboid =

2(lb+bh+hl ) sq.units

We have ,

l = 15 cm

b = 10 cm

h = 5 cm

Total surface area of the given cuboid

=> 2(15×10+10×5+5×15) sq.cm

=> 2(150+50+75 ) sq.cm

=> 2(275 ) sq.cm

=> 550 sq.cm

Diameter of the drilling out cylindrical part = 7 cm

Radius = Diameter/2

Radius of the Cylindrical part = 7/2 cm

Curved Surface Area of the cylinder = 2πrh sq.units

We have , r = 7/2 cm

h = 5 cm

CSA of the Cylindrical part

= 2×(22/7)×(7/2)×(5) sq.cm

=> (2×22×7×5)/(7×2) sq.cm

=> 22×5 sq.cm

=> 110 sq.cm

The part has two circular parts at its end

Area of a circle = πr^2 sq.units

=> (22/7)×(7/2)^2 sq.cm

=>(22/7)×(7/2)×(7/2) sq.cm

=> (22×7×7)/(7×2×2) sq.cm

=> (11×7)/2 sq.cm

=> 772/ sq.cm

Area of two circular ends= 2×(77/2) sq.cm

=> 77 sq.cm

Now ,

The surface area of the remaining block after the circular hole is drilled out

= Total surface area of the cuboidical block + Curved Surface Area of the cylindrical part - areas of two circular ends

=> 550 sq.cm + 110 sq.cm -77 sq.cm

=> 660 sq.cm -77sq.cm

=>583 sq.cm

Answer:-

The surface area of the remaining block after the circular hole is drilled out is 583 sq.cm

Used formulae:-

• Total surface area of a cuboid =
• 2(lb+bh+hl ) sq.units
• Area of a circle = πr^2 sq.units

• Curved Surface Area of the cylinder = 2πrh sq.units
• Radius = Diameter/2

• r=radius
• h =height
• b=breadth
• l=length
• π=22/7

Answer 2

Answer:

Hi baa

i'm ashitha

do you remember ??

Step-by-step explanation: