High number: l is the circle x square + y square; find L (x square + y Square) ds under ∮

High number: l is the circle x square + y square; find L (x square + y Square) ds under ∮

Is l a circle X & # 178; + Y & # 178; = R & # 178;,
Let x = RCOs θ, y = rsin θ
ds=d√(x²+y²)=Rdθ
∮ L (X & # 178; + Y & # 178;) ds = ∮ 0 to 2 π R & # 179; D θ = 2 π R & # 179;