can someone explain the cone cylinder question where it was explain how A=(300+100|2)Pi the cone had radius 10 height 10, cylinder had radius 10 height 10
x Turn on thread page Beta
Edexcel IGCSE Mathematics Higher Tier: 9th June 2016 watch
- Thread Starter
- 09-06-2016 12:28
- 09-06-2016 13:45
The surface area of the cylinder would have been = (Pi x 10squared) + (2 x Pi x 10 x 10) so 200Pi + 100Pi which is 300Pi
Then for the cone you needed pythagoras to find the length and you would do 10squared + 10squred = 200 and then root 200. You would then do Pi x 10 x Root 200 to get 100|2 Pi
Then they are all multiplied by Pi and therefore Pi goes outside the brackets leaving you with A = (300+100|2)Pi
- 09-06-2016 13:46
The Cylinder had the surface area of 2πrh plus the bottom circle which πr^2. This brought the surface area of cylinder to (2π x 10 x 10) + (π 10^2) which gave 300π. Then the curved surface area of the cone was πrl which was π x 10 x 10√2 (had to find the length by doing 10^2 + 10^2 and then squaring rooting 200). This gave you (100√2) π.
So the answer was 300π + (100√2)π which just means you can take out π to leave
(300 + 100root2)π.