Re: [中學] 問一題三角函數證明
theta = 2k
sin(2k) + cos(2k) - 1 = 2sin(k)cos(k) - 2sin(k)sin(k)
= 2sin(k)[cos(k) - sin(k)]
1 - sin(2k) + cos(2k) = 2cos(k)cos(k) - 2sin(k)cos(k)
= 2cos(k)[cos(k) - sin(k)]
LHS = tan(k)
= sin(k)2cos(k) / [cos(k)2cos(k)]
= sin(theta) / [1 + cos(theta)]
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