see when u multply it with itself... u get cos^2(2pi/7)-sin^2(2pi/7) cos2pi/7sin2pi/7-sin2pi/7cos2pi/7 sin2pi/7cos2pi/7+cos2pi/7sin2pi/7 cos^2(2pi/7P+sin^2(2pi/7)
then use cos^2theta-sin^theta to get cos2theta and use sin(a+b) formula then keep multiplying it till u get the answer...that is multiply 7 times..i mean the matrix^7
Moderation Team
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