MATH128 Lecture Notes - Lecture 9: Frustum
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Area of sector is l = l 2 r / 2l = rl, this is the surface area of the cone, cut along l, flatten to make sector of circle with radius l, arc length 2 r, angle. Math 128 dr. smith lecture 9 section 8. 2: area of a surface of revolution. Curve rotated about a line creates a surface: surface area of a right cylinder. Surface area of a cone, base radius r, slant height l. = 2 r / l: we approximate the surface area of a solid with collection of bands formed by rotating a line segment about an axis. Each band is a frustrum, or portion of a circular cone. triangles: finding the formula axis. about the x-axis. 2) dy: if s is length along curve, ds. 2 yds: thus, formula if f(x) is rotated about y-axis.
