Volumes by Cross Sections by Lisa Kramer
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This example demonstrates how to calculate volumes using cross sections. Key mathematical concepts include solid geometry. Construction highlights the use of Plane, Segment, Intersect, Polygon, and other GeoGebra commands. Suitable for high school math education or students learning solid geometry.
GeoGebra Commands & Parameters
Plane((0, 0, 0), (0, 1, 0), (0, 1, 1)) → sPlane((a, 0, 0), (a, 1, 1), (a, 1, 2)) → cPlane((b, 0, 0), (b, 1, 1), (b, 1, 2)) → dSegment((a, f(a)), (a, g(a))) → hSegment((b, f(b)), (b, g(b))) → iIntersect(f, h) → AIntersect(g, h, (-8, -6.968074739870145)) → BIntersect(f, i) → CIntersect(g, i, (8, -1.0319252601298547)) → DPolygon(A, B, (x(B), y(B), h), (x(A), y(A), h)) → q1, a_1, b_1, t, f_1Polygon(A, B, (a, (0.5 * (y(A) + y(B))), (sqrt(3) * h / 2))) → t1, g_1, a_2, b_2Midpoint(A, B) → ESphere(E, A) → uSequence(Polygon[(a + (i * deltax), g(a + (i * deltax)), 0), (a + (i * deltax), f(a + (i * deltax)), 0), 4, s], i, 0, n - 1, 1) → L3Polygon(A, B, (x(B), y(B), h)) → t2, k, a_3, b_3Sequence(Polygon[(a + (i * deltax), g(a + (i * deltax)), 0), (a + (i * deltax), f(a + (i * deltax)), 0), 3, s], i, 0, n - 1, 1) → L4Sequence(Polygon[(a + (i * deltax), f(a + (i * deltax)), 0), (a + (i * deltax), g(a + (i * deltax)), 0), (a + (i * deltax), g(a + (i * deltax)), Distance[(a + (i * deltax), f(a + (i * deltax)), 0), (a + (i * deltax), g(a + (i * deltax)), 0)])], i, 0, n - 1, 1) → L7Line((0, 0, 0), (1, 0, 0)) → mLine((0, 0, 0), (0, 1, 0)) → rTextfield(f) → InputBox1Textfield(g) → InputBox2Textfield(a) → InputBox3Textfield(b) → InputBox4Textfield(n) → InputBox5Sequence(Prism[Element[L3, i], deltax], i, 1, n, 1) → L2Sequence(Prism[Element[L4, i], deltax], i, 1, n, 1) → L5Sequence(Polygon[(a + (i * deltax), g(a + (i * deltax)), 0), (a + (i * deltax), f(a + (i * deltax)), 0), 5, s], i, 0, n - 1, 1) → L6Sequence(Prism[Element[L6, i], deltax], i, 1, n, 1) → L8Sequence(Midpoint[(a + (i * deltax), f(a + (i * deltax)), 0), (a + (i * deltax), g(a + (i * deltax)), 0)], i, 0, n - 1, 1) → L9Sequence((a + (i * deltax), f(a + (i * deltax)), 0), i, 0, n - 1, 1) → L10Sequence(Segment[Element[L9, i], Element[L10, i]], i, 1, n, 1) → radiiSequence((a + (i * deltax), g(a + (i * deltax)), 0), i, 0, n - 1, 1) → L11Sequence(Midpoint[Element[L10, i], Element[L11, i]], i, 1, n, 1) → L12Sequence(CircleArc[Element[L12, i], Element[L10, i], Element[L11, i], s], i, 1, n, 1) → L13Sequence(Prism[Element[L7, i], (-deltax)], i, 1, n, 1) → L