1.

Assertion (A) sum _(r=1)^(n-1) cos^2((rpi)/(n))=(n)/(2)-1 Reasion (R) : cos alpha+ cos (alpha+ beta)+cos(alpha+2 beta)+....+cos (alpha(n-1) beta)=(sin(n beta//2))/(sin(beta//2)). Cos ((2 alpha+(n-1) beta)/(2))

Answer»

A is TRUE, R is true and R is CORRECT explanation of A
A is true, R is true and R is not correct explanation of A
A is true, R is false
A is false, R is true

Answer :A


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