- #1
Theofilius
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Homework Statement
Hi
Find the (finite,ultimate,definitive,peremptory,eventua,conclusive) sum:
[tex]a) cos^2x+cos^22x+...+cos^2nx ; b) sin^2x+sin^22x+...+sin^2nx [/tex]
Homework Equations
z=A+Bi
The Attempt at a Solution
[tex]A=cos^2x+cos^22x+...+cos^2nx[/tex]
[tex]B=sin^2x+sin^22x+...+sin^2nx[/tex]
[tex]z=cos^2x+cos^22x+...+cos^2nx+i(sin^2x+sin^22x+...+sin^2nx)=(cos^2x+isin^2x)+(cos^22x+isin^22x)+...+(cos^2nx+isin^2nx)=(cos^2x+isin^2x)+[/tex]
[tex](cos^2x+isin^2x)^2+...+(cos^2x+isin^2x)^n[/tex]
How will I continue?
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