G the base of a solid is the circle x2 + y2 = 9. cross sections of the solid perpendicular to the x-axis are equilateral triangles. what is the volume, in cubic units, of the solid

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Mathematics

Katrina Taylor

29 June, 20:09

G the base of a solid is the circle x2 + y2 = 9. cross sections of the solid perpendicular to the x-axis are equilateral triangles. what is the volume, in cubic units, of the solid

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Irene Nash · Answer 1

The base of a solid is the circle x2 + y2 = 9. Cross sections of the solid perpendicular to the x-axis are equilateral triangles. What is the volume, in cubic units, of the solid?

Each triangle has a base 2y. So, since the area of an equilateral triangle of side s is √3/4 s^2, our triangles have area.

√3/4 (9-x^2)

Now, all we have to do is sum up all the triangular plates of thickness dx, from - 3<=x<=3. Or, because of symmetry, twice the volume for 0<=x<=3.

v = 2∫[0,3] √3/4 (9-x^2) dx