A wooden toy rocket is in the shape of a cone. The height of the conical part is 12cm. The base of the conical portion has a diameter of 10cm. If the conical portion is to be painted red and the base portion green. Find the area of the rocket to be painted (use ⫪=3.14)
3
Answers
Answer:
Let r be the radius of the base of the
cone and it's slant height be ' l ' .
Let r1 be the radius of cylinder and h1
be it's height
We have ,
r = 2.5 cm , h = 6 cm
r1 = 1.5 cm , h1 = 20 cm
Now ,
l = √ r² + h²
=> l = √ ( 2.5 )² + 6²
l = √ 6.25 + 36
l = √ 42.25
l = 6.5 cm
Now ,
area to be painted orange CSA of
the cone + base area of the cone
- base area of the cylinder
= πrl + πr² - πr1²
= π{ 2.5×6.5)+(2.5)² - ( 1.5 )² } cm²
= π ( 20.25 ) cm²
= 3.14 × 20.25 cm²
= 63.585 cm²
Area to be painted yellow
= CSA of the cylinder + Area of base of
the cylinder
= 2πr1h1 + πr1²
= πr1( 2h1 + r1 )
= 3.14 × 1.5 ( 2 × 20 + 1.5 ) cm²
= 3.14 × 1.5 × 41.5 cm²
= 4.71 × 41.5 cm²
= 195.465 cm²
Therefore ,
area to be painted yellow = 195.465 cm²
I hope this helps you.
: )