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Kalid’s “Gentle introduction to calculus”. Using the circle. Take any circle:. Draw as many rings inside the circle as you can:. “Unroll” the rings and line them up like this:. If you split the circle into more rings. If you split the circle into more rings...they’d be skinnier than these.
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Kalid’s “Gentle introduction to calculus” Using the circle Concept by Kalid Azad Slide Show by Audrey McGoldrick
Take any circle: Concept by Kalid Azad Slide Show by Audrey McGoldrick
Draw as many rings inside the circle as you can: “Unroll” the rings and line them up like this: Concept by Kalid Azad Slide Show by Audrey McGoldrick
If you split the circle into more rings... Concept by Kalid Azad Slide Show by Audrey McGoldrick
If you split the circle into more rings...they’d be skinnier than these... Concept by Kalid Azad Slide Show by Audrey McGoldrick
If you split the circle into more rings...they’d be skinnier than these... ...and this would become... Concept by Kalid Azad Slide Show by Audrey McGoldrick
If you split the circle into more rings...they’d be skinnier than these... ...and this would become... ...this!... Concept by Kalid Azad Slide Show by Audrey McGoldrick
If you split the circle into more rings...they’d be skinnier than these... ...and this would become... ...this!... ...which is even prettier, and closer to a right triangle! Concept by Kalid Azad Slide Show by Audrey McGoldrick
If you do this long enough, eventually you will have... Concept by Kalid Azad Slide Show by Audrey McGoldrick
If you do this long enough, eventually you will have... ...this triangle... Concept by Kalid Azad Slide Show by Audrey McGoldrick
...whose area must equal the area of the original circle! Concept by Kalid Azad Slide Show by Audrey McGoldrick
This side must be the radius of the circle Concept by Kalid Azad Slide Show by Audrey McGoldrick
r r Concept by Kalid Azad Slide Show by Audrey McGoldrick
..and this side must be... r r Concept by Kalid Azad Slide Show by Audrey McGoldrick
..and this side must be... ..its circumference! r r Concept by Kalid Azad Slide Show by Audrey McGoldrick
r 2r r Concept by Kalid Azad Slide Show by Audrey McGoldrick
Use that good old formula for area of a triangle.... r 2r r Concept by Kalid Azad Slide Show by Audrey McGoldrick
Use that good old formula for area of a triangle... r·2r r 2r 2r r Concept by Kalid Azad Slide Show by Audrey McGoldrick
Use that good old formula for area of a triangle...and with a bit of algebra: r2 r·2r r 2r r Concept by Kalid Azad Slide Show by Audrey McGoldrick
And voila! Concept by Kalid Azad Slide Show by Audrey McGoldrick