1.

on 1) oRe T 3R S Itan 20 tan 20 tan 54 tan 55

Answer»

tan(π/20) tan(3π/20) tan(5π/20) tan(7π/20) tan(9π/20) = 1.

To this end:tan(π/20) tan(3π/20) tan(5π/20) tan(7π/20) tan(9π/20)= tan(π/20) tan(3π/20) tan(5π/20) cot(π/2 - 7π/20) cot(π/2 - 9π/20)via cofunction identity

= tan(π/20) tan(3π/20) tan(5π/20) cot(3π/20) cot(π/20)= tan(π/20) tan(3π/20) tan(5π/20) * 1/tan(3π/20) * 1/tan(π/20)= tan(5π/20)= tan(π/4)= 1.



Discussion

No Comment Found