0≤θ≤π, cos4θ=cos2θ https://www.wolframalpha.com/input?key=&i=0%E2%89%A4%CE%B8%E2%89%A4%CF%80%2C+cos4%CE%B8%3Dcos2%CE%B8&lang=ja グラフがでます。 cos4θ,cos2θ,0≤θ≤π https://www.wolframalpha.com/input?key=&i=cos4%CE%B8%2Ccos2%CE%B8%2C0%E2%89%A4%CE%B8%E2%89%A4%CF%80&lang=ja
0≤θ≤π, cos4θ=cos2θ
https://www.wolframalpha.com/input?key=&i=0%E2%89%A4%CE%B8%E2%89%A4%CF%80%2C+cos4%CE%B8%3Dcos2%CE%B8&lang=ja
グラフがでます。
cos4θ,cos2θ,0≤θ≤π
https://www.wolframalpha.com/input?key=&i=cos4%CE%B8%2Ccos2%CE%B8%2C0%E2%89%A4%CE%B8%E2%89%A4%CF%80&lang=ja