Optimized Circle Inscribed in an Isosceles Triangle
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This example demonstrates finding the largest circle that can be inscribed in an isosceles triangle, which is the incircle tangent to all three sides)Skip. It visually shows how the circle's radius and area change as the triangle's shape varies, linking geometry with optimization. Core mathematical concepts include properties of incircles, angle bisectors meeting at the incenter, perpendicularity of radius to tangent sides, and maximizing area under constraints. Construction uses GeoGebra commands: Point, AngularBisector, Intersect, Segment, OrthogonalLine, and Circle, creating vertices A, B, C, angle bisectors e and d, incenter D, perpendicular f to base, tangency point E, radius r, and auxiliary objects like a, b, area text. Suitable for high school or early college students, this interactive applet supports geometric construction practice, dynamic exploration, and intuitive understanding of optimization problems, serving as a visual prelude to calculus-based extremum problems.
GeoGebra Commands & Parameters
Point(Circle[A, 1]) → BPoint(Circle[B, 1]) → CAngularBisector(A, C, B) → eAngularBisector(B, A, C) → dIntersect(d, e) → DSegment(A, C) → BaseOrthogonalLine(D, Base) → fIntersect(f, Base) → ESegment(D, E) → rSegment(A, B) → aSegment(B, C) → bIntersect(f, Base) → FCircle(D, F) → cOrthogonalLine(D, a) → gIntersect(c, g, 2) → GSegment(G, D) → hOrthogonalLine(D, b) → iIntersect(c, i, 2) → HSegment(D, H) → j
AI Drawing Prompt Reference
Draw an isosceles triangle with a horizontal base. Construct the angle bisectors from the two base angles, and let them intersect at a point inside the triangle, which is the incenter. Drop a perpendicular from the incenter to the base, marking the foot on the base. Draw a circle centered at the incenter with radius equal to the distance from the incenter to that foot, so the circle is tangent to all three sides. Also drop perpendiculars from the incenter to the two equal sides, marking their feet on the circle. Allow adjusting the triangle's apex to see how the incircle changes.
The prompt above was compiled from the original drawing commands and is for reference only.