Finding the exact value of sin(18 degrees)
This is one classic way to find the exact value of sin(18 degrees), i.e sin(pi/10). We will use the double angle identity for sin(2x), the triple angle identity for cos(3x) (proof here 👉    • cos(3x) in terms of cos(x)  ), and the quadratic formula! I love this so much because this covers so much! Enjoy! sin(18 degrees) by using a special right triangle:    • this special triangle gives us sin(18º)  ---------------------------------------- 💪 Support this channel and get my math notes by becoming a patron:   / blackpenredpen  🛍 Shop my math t-shirt & hoodies: https://amzn.to/3qBeuw6 ----------------------------------------
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They changed the sine to cosine!
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exact value of sin(10 degrees)
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The sine triangle problem
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this special triangle gives us sin(18Âş)
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The Exact Value for Tangent of 18 Degrees, tan(18)
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How Euler would integrate sqrt(x^2+1)
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finding sin(18°) without trigonometry
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Derivatives Aren't What You Think They Are
![Proofs: Lim sinx/x =1 and lim [cosx -1] /x =0 as x goes to zero from geometry](https://i.ytimg.com/vi/W0jiodfVGx0/hqdefault.jpg?sqp=-oaymwEjCNACELwBSFryq4qpAxUIARUAAAAAGAElAADIQj0AgKJDeAE=&rs=AOn4CLC1sRa1ugKKc5vzqNWdsn98a95SJA)
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Proofs: Lim sinx/x =1 and lim [cosx -1] /x =0 as x goes to zero from geometry
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I found the exact value of sin 1 degree (from sin 3 degrees) | Inspired by @blackpenredpen
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We must do this do this carefully!
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exact value of sin(3 degrees)
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Math for fun, sin(sin(z))=1
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Someone improved my code by 40,832,277,770%
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All the TRIG you need for calculus actually explained
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If You Have A Bad Memory, I’ll Help You Fix It In 28 Minutes
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"Teacher, can you do the integral of sqrt(x^2+1)/x?"
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08 - Calculate Sin, Cos & Tan w/ Unit Circle in Radians - Part 1
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This Integral Will Make You Better At Calculus
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