What is the arclength of r=5/2sin(theta/8+(3pi)/16) -theta/4r=52sin(θ8+3π16)θ4 on theta in [(-3pi)/16,(7pi)/16]θ[3π16,7π16]?

1 Answer
May 13, 2016

s = 2.72416s=2.72416

Explanation:

In polar coordinates ds^2 = r(theta)^2+((d r(theta))/(d theta))^2ds2=r(θ)2+(dr(θ)dθ)2
here r(theta)=5/5sin(theta/8+(3pi)/16)-theta/4r(θ)=55sin(θ8+3π16)θ4
(dr(theta))/(d theta) =-1/4+5/16cos((3pi)/16+theta/8) dr(θ)dθ=14+516cos(3π16+θ8) doing
int_((-3pi)/16)^((7pi)/16)sqrt(r(theta)^2+((d r(theta))/(d theta))^2)d theta = 2.724167π163π16r(θ)2+(dr(θ)dθ)2dθ=2.72416