Question

Plz...solve it... class 9th​

Answer 1

✧ Given :-

• The diameter of the cone = 40cm.,
• Radius (r) = 20cm. or, 0.20m.,
• And, Height = 1m.

✧ To find :-

• Cost of painting of the cones = ??

✧ Solution :-

• Here, we have to find the curved surface area of each cones
• Thereafter the curved surface area of such 50 cones.
• The rate of 12per sq.m.

$\therefore \bf \: Slant \: height \: = \sqrt{ {r}^{2} + {h}^{2} } \\ \bf = \sqrt{ {0.2}^{2} + {1}^{2} } \\ \sf = \sqrt{ {0.04} + 1} \\ \sf \: = \sqrt{1.04} ={ \boxed{ \boxed{ 1.02m.}}}$

Now,

$\sf \: Curved \: surface \: area \: of \: each \: cone = \pi \: rl \\ \sf = 3.14 \times 0. 2\times 1.02 \\ \sf \: = 0.64056 {m}^{2}$

$\bf \therefore \: curved \: surface \: area \: of \: such \: 50 \: cones \\ \sf = 0.64056 \times 50 \\ \sf \: = 32.028 {m}^{2}$

$\bf \therefore cost \: of \: painting \: at \: the \: rate \: of \: 12per {m}^{2} \\ \sf \: = ₹( 32.028 \times 12 )\\ {\boxed{\boxed{ \sf =\green{ ₹ 384.34} \: (approx.)}}}$

Answer 2

Answer:

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