Determine whether the tests for symmetry detect symmetry with respect toa. The polar axis. Replace (r,θ) by (r,−θ).b. The line θ=2π. Replace (r,θ) by (r,π−θ).c. The pole. Replace (r,θ) by (−r,θ).r2=9sin2θ
Q. Determine whether the tests for symmetry detect symmetry with respect toa. The polar axis. Replace (r,θ) by (r,−θ).b. The line θ=2π. Replace (r,θ) by (r,π−θ).c. The pole. Replace (r,θ) by (−r,θ).r2=9sin2θ
Test Symmetry Polar Axis: a. Test for symmetry with respect to the polar axis by replacing (r,θ) with (r,−θ).Original equation: r2=9sin(2θ)Replace θ with −θ: r2=9sin(2(−θ))=9sin(−2θ)Since sin(−x)=−sin(x), we have: r2=9(−sin(2θ))=−9sin(2θ)This does not match the original equation, so there is no symmetry with respect to the polar axis.
Test Symmetry Line: b. Test for symmetry with respect to the line θ=2π by replacing (r,θ) with (r,π−θ).Original equation: r2=9sin(2θ)Replace θ with π−θ: r2=9sin(2(π−θ))=9sin(2π−2θ)Since sin(2π−x)=sin(x), we have: r2=9sin(2θ)This matches the original equation, so there is symmetry with respect to the line θ=2π.
Test Symmetry Pole: c. Test for symmetry with respect to the pole by replacing (r,θ) with (−r,θ).Original equation: r2=9sin(2θ)Replace r with −r: (−r)2=9sin(2θ)Since (−r)2=r2, we have: r2=9sin(2θ)This matches the original equation, so there is symmetry with respect to the pole.