A solid cylinder of radius 7cm is 10cm long.find it's total surface area
a. 70πcm3
b. 210πcm3
c. 238πcm3
d. 189πcm3

C.  238π  cm^3.

Step-by-step explanation:

Surface area = 2 * area of the circular ends + area of the curved length

= 2π r^2 + 2π r* l

= 2 π 7^2 + 2π 7 * 10

= 98π + 140π

= 238π  cm^3.

c. 238πcm3

Step-by-step explanation:

Total surface area =

2pirh + 2pir^2

Given radius r = 7cm and

Height h = 10cm

Total surface area = 2 x pi x 7 x 10 + 2 x pi x (7)^2

140pi + 2 x pi x 49

140pi + 98pi

238pi cm^3

Answer :-

9(3+√3) feet

Step by step explanation :-

A triangle is given to us. In which one angle is 30° and length of one side is 18ft ( hypontenuse) .So here we can use trignometric Ratios to find values of rest sides. Let's lable the figure as ∆ABC .

Now here the other angle will be = (90°-30°)=60° .

In ∆ABC ,

=> sin 30 ° = AB / AC

=> 1/2 = AB / 18ft

=> AB = 18ft/2

=> AB = 9ft .

Again In ∆ ABC ,

=> cos 30° = BC / AC

=> √3/2 = BC / 18ft

=> BC = 18 * √3/2 ft

=> BC = 9√3 ft .

Hence the perimeter will be equal to the sum of all sides = ( 18 + 9 + 9√3 ) ft = 27 + 9√3 ft = 9(3+√3) ft .