Use the formula:
S=Integral
2pi y ds, y=f(x)=sinx
S=Integral 2pi sin x
ds
Calculate ds
with:
ds=sqrt(1+(dy/dx)^2)
calculate
dy/dx=cosx => ds=sqrt(1+(cos x)^2)
Calculate
S:
S = Integral 2pi sin xsqrt(1+(cos x)^2)
dx
Let (cos x)=k=> (cos x)'=k' => -sin
x=dk/dx
S = -Integral 2pi sqrt(1+(k)^2) dk=-2pi Integral
sqrt(1+(k)^2)
dk
S=(-2pi/2)(ksqrt(1+(k)^2)+ln(k+sqrt(1+(k)^2)))
Do
the substitution k=cos x
S=pi(cos 0sqrt(1+(cos0)^2)+ln(cos
0+sqrt(1+(cos 0)^2)-cos (pi/2)sqrt(1+(cos(pi/2))^2)-ln(cos (pi/2)+sqrt(1+(cos
(pi/2))^2)))
S=pi(sqrt2+ln(1+sqrt2)-ln(0+sqrt1))
S=pi(sqrt2+ln(1+sqrt2)-ln(1))
S=pi(sqrt2+ln(1+sqrt2)-0)
S=pi(sqrt2+ln(1+sqrt2))
Answer:
the lateral surface of the solid of
revolution:S=pi(sqrt2+ln(1+sqrt2))
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