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Golden sine (Posted on 2023-09-17) Difficulty: 2 of 5
Prove that sin318 + sin218 = 1/8.

No Solution Yet Submitted by Danish Ahmed Khan    
Rating: 4.0000 (1 votes)

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Solution re: proof found | Comment 2 of 3 |
(In reply to proof found by Steven Lord)

Sin 18 degrees = (v5-1)/4

=> sin^2(18) = (3-v5)/8
Now, sin^3(18)+ sin^2(18)
=sin^2(18)(sin(18)+1)
= (3-v5)/8* (v5+3)/4
= (9-5)/32
=4/32
=1/8

Edited on September 17, 2023, 11:00 pm
  Posted by K Sengupta on 2023-09-17 23:00:04

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