Question

Find 1.the slant height 2.the curved surface area and 3.total surface area of a cone,if it's base radius is 12cm. and height is 16cm.

Answer 1

Hello friend
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=) In the example

Given: Radius,r = 12cm

height,h = 16cm.

i.) Slant height

as we know that,

l^2. = r^2 + h^2

l^2 = (12)^2 + ( 16)^2

l^2 = 144 + 256

l^2 = 400

l = 20.

therefore the slant height = 20cm.

ii.) Curved surface area of cone = pi *r*l

= 3.14*12*20

= 753.6 cm^2.

therefore the curved surface area of cone = 753.6 cm^2.

iii.) Total surface area of cone = pi*r(l+r)

= 3.14*12(20+12)

= 3.14*12*32

= 1205.76 cm^2.

I hope this will helps you.

Thanks..

Answer 2

R=12cm
H= 16cm 
 1.  TO find the slant height we cann use the pythagoreous theorem i whicch 
L²=R²+H²
THAT IS 
L²= 12²+16²
L²=36,864
L=192cm

2. u can find the CSA b y the formula πrl

= 22÷7  ×12×192
=7241.142

3. TSA=πr(r+l)

=22÷7×12(12+192)
ull get the answer =7693.714

i think itll be better to use π=3.14