Circle Area Formula Demonstration
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This example dynamically demonstrates the derivation of the circle area formula. It involves core math concepts like circle, area calculation, and geometric construction. GeoGebra commands and objects used include Segment, Point, Circle, Rotate, Sector. Suitable for middle school and above students to understand the geometric meaning and derivation of the formula.
GeoGebra Commands & Parameters
Segment(E, (x(E) + 2, y(E))) → aPoint(a) → FMin(x(F) - x(E), 1) → kPoint(yAxis) → OSequence(If[k < 1, (x(O) + ((l * sin((i * φ))) * cos((i * φ)) / sin(φ)), y(O) + ((l * sin((i * φ))) * sin((i * φ)) / sin(φ))), (x(O) + (l * i), y(O))], i, 0, (2 * n)) → list2Sequence((x(O) + sin((i * θ)), y(O) + 1 - cos((i * θ))), i, 0, (2 * n)) → list1Max(x(F) - x(E) - 1, 0) → k'Rotate((x(O) + 0, y(O) + 1), ((-k) * θ / 2), O) → ARotate(O, ((-k) * θ / 2), O) → O'Rotate(Element[list1, 1], ((-k) * θ / 2), O) → BSector(Rotate[Circle[(x(O) + 0, y(O) + 1), O], ((-k) * θ / 2), O], Rotate[O, ((-k) * θ / 2), O], Rotate[Element[list1, 1], ((-k) * θ / 2), O]) → cRotate((x(O) + 0, y(O) + 1), ((-k) * θ / 2), O) → CRotate(O, ((-k) * θ / 2), O) → O'_1Rotate(Element[list1, 1], ((-k) * θ / 2), O) → DArc(Rotate[Circle[(x(O) + 0, y(O) + 1), O], ((-k) * θ / 2), O], O'_1, D) → dCurveCartesian(t - sin(t), 1 - cos(t), t, 0, 6.28319) → bCircle((0, 1), 1) → hRay((0, 0), (1, 0)) → iPoint(Segment[(0, 1), (6.28319, 1)]) → HSegment(H, (x(H), 0)) → jMidpoint(j) → IMidpoint(a) → JCircle(L, 1 / (1 - m)) → pCircle((0, 0), 1 / (1 - m)) → qIntersect(p, q, 1) → MIntersect(p, q, 2) → NCircle((0, 1), 1) → c_1Segment((0, 0), (6.283185307179586, 0)) → eSegment(G, (x(G), y(G) - 1)) → rCircleArc((0, 1 / (1 - m)), O, L) → sSequence(Midpoint[Element[list2, i], Element[list2, i + 1]] + (l / ((2 * tan(θ / 2))) * UnitOrthogonalVector[Vector[Element[list2, i], Element[list2, i + 1]]]), i, 1, (2 * n) + 1) → list5Sequence(CircleSector[Element[list5, i], Element[list2, i], Element[list2, i + 1]], i, 1, n) → list3Sequence(Rotate[CircleSector[Element[list5, i], Element[list2, i], Element[list2, i + 1]], (180° * k'), (((n + 0.75) * l) - (sin(θ / 2) * 2), cos(θ / 2) / 2)], i, n + 1, (2 * n) + 1) → list4
AI Drawing Prompt Reference
Draw a circle and demonstrate the derivation of its area formula. Start by drawing a line segment from the center to the circumference, then create a point on the segment. Next, draw a sector with the central angle equal to half the circle's circumference. Rotate and divide the sector into multiple small sectors, each approximating a triangle in area. Sum the areas of these small sectors to visualize the derivation of the area formula.
The prompt above was compiled from the original drawing commands and is for reference only.