Question

Prove: $\sin\frac{\pi}{20}+\cos\frac{\pi}{20}+\sin\frac{3\pi}{20}-\cos\frac{3\pi}{20}=\frac{\sqrt2}{2}$

score 838 · Answer 1 · 2018-07-21 13:31:56

838

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Prove: $\sin\frac{\pi}{20}+\cos\frac{\pi}{20}+\sin\frac{3\pi}{20}-\cos\frac{3\pi}{20}=\frac{\sqrt2}{2}$

Published on 21 Jul 2018 - 13:31

score 109 · Answer 2 · 2018-07-21 16:58:40

109

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91

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1.3k

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839

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score 1.5k · Answer 15 · 2018-07-25 03:51:53

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List Question

Prove: $\sin\frac{\pi}{20}+\cos\frac{\pi}{20}+\sin\frac{3\pi}{20}-\cos\frac{3\pi}{20}=\frac{\sqrt2}{2}$

Is there a simpler way to determine m, n, p, such that the following holds for all reals?

Why does the Maclaurin series of sin(x) converge to sin(x)?

Is $\cosh(z)\exp(iz)+ \sin(i\overline{z})\exp(z)$ complex differentiable.

Impulse train: why an indeterminate result?

Proofs for the Spherical Laws of sines and Cosines

Given some $x ∈ ℝ$, find some $y ∈ ℝ: x < y < \left \lfloor {x+1} \right \rfloor $

Point in Coordinate System A, how to find its location in Coordinate System B?

Proving a long-ish trig identity

Find the number of solutions of $\cos x=\frac{\lvert x \rvert}{80}$

How to Prove $a^3 \cos (B-C) + b^3 \cos (C-A)+ c^3 \cos (A-B)=3abc$?

How to get bounding box around objects?

If matrix $A$ has entries $A_{ij}=\sin(\theta_i - \theta_j)$, why does $\|A\|_* = n$ always hold?

Trig/Precalculus help! Airplane bearing and distance from mountain

Number of solutions of $2^{\cos x}=|\sin x|$

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