sin( π/8) + sin(3 π/8)+sin(5π/8)+sin(7π/8)
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Sin²π/8+sin²3π/8+sin²5π/8+sin²7π/8
=sin²π/8+sin²3π/8+sin²(π/2+π/8)+sin²(π/2+3π/8)
=sin²π/8+sin²3π/8+cos²π/8+cos²3π/8
=(sin²π/8+cos²π/8)+(sin²3π/8+cos²3π/8) [∵, sin²Ф+cos²Ф=1]
=1+1
=2 Ans.
=sin²π/8+sin²3π/8+sin²(π/2+π/8)+sin²(π/2+3π/8)
=sin²π/8+sin²3π/8+cos²π/8+cos²3π/8
=(sin²π/8+cos²π/8)+(sin²3π/8+cos²3π/8) [∵, sin²Ф+cos²Ф=1]
=1+1
=2 Ans.
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