例) f(θ)=-√3sinθ+√3cosθ
rsin(θ+α)=rsinθcosα+rcosθsinα
=rcosαsinθ+rsinαcosθ
rcosα=-√3, rsinα=√3
r²=(rcosα)²+(rsinα)²=(√3)²+(√3)²=6
r=√6 (r＞0)
cosα=(rcosα)/r=-√3/√6=-1/√2
sinα=√3/√6=1/√2
α=3π/4
0≦θ＜2π
3π/4≦θ+3π/4＜11π/4
-1≦sin(θ+3π/4)≦1
MAX: sin(θ+3π/4)=1
θ+3π/4=5π/2 (3π/4≦θ+3π/4＜11π/4)
θ=7π/4
f(θ)=√6sin(θ+3π/4)
f(7π/4)=√6×1=√6
…
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r²=(√2)²+(√6)²=8
r=√8=2√2
cosα=√2/2√2=1/2,
sinα=√6/2√2=√3/2
α=π/3
0≦θ＜2π
π/3≦θ+π/3＜2π+π/3
-1≦sin(θ+π/3)≦1
MAX: sin(θ+π/3)=1
θ+π/3=π/2 (π/3≦θ+π/3＜2π+π/3)
θ=π/6
f(θ=π/6)=2√2×1=2√2
min: sin(θ+π/3)=-1
θ+π/3=3π/2 (π/3≦θ+π/3＜2π+π/3)
θ=7π/6
f(θ=7π/6)=2√2×(-1)=-2√2
